@kigmatzomat I think that is a much more functional way to look at the problem. The question isn't really "what's typical in fiction", but what's typical in the campaign that I'm running. Establishing demographics is IMO one of the most important things a DM can do when preparing a campaign because it informs your sandbox play and gives you some standard for what newly invented content ought to conform to. What level is the bartender? What does your demographics say is likely?
Typically, I'm asking questions like: "What percentage of the population are members of each class?" How common are characters of a particular level and a particular class? At what age does a person typically obtain a higher level?
Typically, in my game I think about characters in terms of tiers, and typically this is how I tier.
1st-3rd level: "Realistic" tier. Lots of characters exist at these levels with an almost even distribution - there are almost as many 3rd level characters out there as 1st level characters. Most NPCs can expect to obtain about 3rd level if they live long enough, but in most cases the levels will be in mundane classes: commoner, expert, brute, scholar, warrior, explorer, plus a smattering of levels in fighter or rogue if the character spent part of their life in risky situations or receiving highly skilled training. What is typical is that higher leveled characters are older. You'd rarely find a character who was 3rd level who was less than 40 years old because NPCs typically aren't adventuring but acquiring XP slowly through mundane life experiences. Likewise, the feats and skills acquired by typical NPCs will be focused on mundane survival and not facing off against monsters in dark places. They'll be good at farming, crafts, and social skills. And the ability scores of these characters are typically quite ordinary - 11, 11, 11, 10, 10, 10 - slightly modified depending on the characters profession. A stevedore might have 16 STR or a scholar might have 16 INT, but if so then they'll probably have no higher than 10 in any other ability. Characters in this tier tend to treat 10 as a fairly high ability score, and 12 as extraordinary talent.
4th-6th level: "Heroic" tier. These characters represent more or less the peak of realistic human ability. Protagonists in "realistic" or "gritty" movies tend to be about this level. They are uncommon and each step up is rare. For commoners there are probably 1/3rd many characters of each level as the proceeding one. For PC classes there are maybe as few as 1/6th as many characters of each level up as the next (especially if the region isn't known for producing members of that class). For example, in an urban area, a group of 1000 fighters you might expect only 1 6th level fighters, 9 5th level fighters, 52 4th level fighters, but 313 3rd level fighters 313 2nd level fighters, and 313 1st level fighters. Notice how quickly things drop off. If fighters represent like 3% of the population, then in a city of around 33,000 people there is like 1 6th level fighter. Compare that demographics to the 3e rules you posted where on average in a city of that size there would be like 456 1st, 228 3rd, 144 5th, 72 7th, 36 9th, 18 11th, 9 13th, 5 15th, 3 17th, and 1 19th level fighter. Compared to the setting you think is default, a 7th level character is extraordinarily important, but ordinary competency is actually on average higher in my demographics. The default city protects itself with a few high-level heroes each of which is a demigod in power. My city protects itself with a competent army, each member of which would be out of his depth (put intended) in a typical dungeon. In the default city, it's really hard to imagine what could possibly threaten the city. An army of high challenge monsters would be required. My city could conceivably defend itself against something CR 10 or CR 12 at considerable loss of life, but anything more than that is a stretch. Yet, monsters have similar demographics. In the default city, it's hard to imagine what a group of 1st level characters could do that wouldn't already have been done by someone more competent at the task. "Treasure to be found here" would have long ago assembled a party of tomb raiders and heroes decades ago. In my city, it's easy to see why nearby sources of danger would be generally avoided. Particularly when you consider that typical 6th level NPCs are past their adventuring prime and might be built on something like a 15,13,12,11,10,9 ability score array and really do have other things that they can be doing, like being critical leaders in their community. And also, because that's the demographics I have, it's unlikely the shop keeper is a 10th level fighter to punish the PCs in the meta because I don't like that they are stealing. The shop keeper is probably a competent 3rd level expert and the larger society does have mechanisms to deal with high level threats, but my meta isn't determined by out of fiction considerations like "I want you stealing from the monsters and not the shop keeper."
7th-11th level: "Super-heroic tier": This is the level of less gritty action-adventure movies to the level of lower tier superheroes. Typically, this level represents the most powerful characters in a nation or small region. These are the elite movers and shakers of society. At the upper limits of this tier, there are only a few of these per 100,000 individuals.
12th-16th level: "Global Influencer": There are a few of these per million mortals. This is the level of the most powerful mortal individuals on the planet. These are the leaders of cults and religious sects, the mightiest spellcasters, the greatest military leaders, the most powerful crime bosses, etc. No commoners exist at this level, because this level you don't obtain just by living a normal life. Anyone forced by life circumstances to level up like this would not be gaining the experience of a commoner.
17th-20th level: "Veritable demigod": There isn't a guarantee that a living example of a character of a particular class exists at this level at any given time and the few that do exist are typically living legends. Only a few characters of this level arise per culture per century. Many of the existing ones are characters who managed to extend their life in some fashion. Characters of this level rarely face any challenges in the mortal world and would probably have to adventure outside of the mortal realm to find challenges suitable to their talents.
A lot of fantasy novels have similar tiering IMO, although in some cases the narrative is focused on that protagonist or protagonists who are breaking the curve. For example, the D&D inspired early Raymond Faust novels are probably tiered as above but Pug and Tomas are breaking the curve and rapidly hit "veritable demigod" status. Tolkien arguably tiers at about this level or below, where you can argue for historic characters like Luthien, Fingolfin, Hurin, and Eärendil of the legendary past being in that 17th-20th level range, but by the time of the late Third Age even characters like Gollum, Gandalf and Aragorn are topping out in the 7th or 8th level range and the big baddies aren't even in the 17th-20th level range (Sauron without his ring, for example). Glorfindel and Galadriel might be topping out in the range of 10th or 11th level as the highest-level characters in middle earth that aren't Sauron. Tamora Pierce's "Tortall" universe has I think similar tiering. Robert Howard's "Conan" has I think similar tiering.
I can't even recognize how something like Faerun works. It's much closer to a DC Superheroes setting, and a I really feel that it's a setting that doesn't closely examine the implications of the setting. Certainly you can't explain NPCs levelling up through any mechanism remotely similar to how PCs level up, and yet somehow NPCs seem to exceed PCs in level. Shouldn't the PC's be doing whatever the NPCs do since it seems easier and less dangerous, and then go on adventures once the threat is mitigated?
