And once again, the value that you're using as "maximum effective range" is not the value that we're discussing.
If you look at this in D&D terms, it might be a little more empirical as to what we are talking about. (I'm going to discuss 3e because that's what I'm familiar with, but you can translate this into 5e.)
Hitting a stationary man sized target is DC 5. If the range increment of a pistol is say 30 feet, then we'd expect even a novice to hit a paper target fairly reliably. This is especially true in that a modern semi-automatic pistol has a fairly high inherent accuracy bonus (let's say +3) in that it's a better than masterwork quality flat shooting high velocity weapon that doesn't at close ranges require a user to compensate for ballistic flight or anything of the such. If we move the target further away, it will be increasingly hard to hit the target since every 30 feet back adds a -2 to hit, but even a DC 11 at 40 yards is not a difficult shot. Or hypothetical novice with a +3 bonus to hit still needs but an 8 plus, and as this is a simple weapon proficiency would be acquired very rapidly - basically after a time or two at the range.
A good 'grouping' on such a target isn't that hard either. Now we are talking about a diminutive target, so effective -4 to hit, or a DC of 9. Again, at 30 feet this isn't that hard.
The hypothetical routine shooter in D&D terms might be someone with a 14 Dex, who is a 4th level Expert (maybe trading for a couple levels of fighter if he's been a soldier or law enforcement officer), and has Weapon Focus (Handgun). He routinely puts a grouping within 4" at 10 or 20 yards, and often gets a good grouping at 30 or 40 yards.
But, put this person in a combat situation, and things get much harder in a hurry. At the least, hitting a live target in D&D is DC 10 rather than DC 5, and higher if the target has DEX. In a fire fight, very likely you are also talking about both the shooter and the target taking a defensive action because bullets, so now you are talking a -4 penalty to hit and a target DC of 12 or higher. Once you start putting some range increments into the fight, and once the target has partial cover, actually landing a bullet starts getting fairly hard even for someone like an FBI agent who has put a lot of time in on the firing range.
If you further add some firefight realism that D&D typically ignores because it's not focused on this sort of thing, by considering unaimed 'snap' shots, firing while moving, and firing at a moving target, you can see why in an actual fire fight you usually have large numbers of shots fired by both sides. Speaking of the FBI, there are some important historical cases that come to mind, such as the 1986 FBI Miami shootout, where a combination of all the above circumstances with low low stopping power weapons by the FBI agents lead to a prolonged bloody firefight.
Remember, in D&D terms, a pistol with a 30' range increment - which might be typical for a short barreled weapon - has an "maximum effective range" of over 100 yards (200 yards if you have the 'far shot' feat or equivalent). But good luck hitting at this range in combat with a -20 to hit on top of your other problems. The practical range of the weapon is going to be much lower - say 20-30 yards depending on the users skill. (Also, if we are being gritty in our realism, the real world doesn't have any 20th level characters - even 6th level is a pretty epic person in real life. Also, if we are being hyper realistic, D&D isn't a great system for doing it, but then again few RPGs really are).
