That someone better
Now sure, obviously, D&D is not meant to simulate reality. But at the same time, insisting on huge margins for failure for PC's, when we have to assume this doesn't hold true for NPC's (or the world would quickly come to a crashing halt) really detracts from the "role-playing" side of the role-playing game.
This is a non issue in skill based games. I think that it is largely a matter of conflicting expectations due to the way D&D scales combat damage and HP, vs. its skill progression.
Now, many DMs might say unless there is a reason why a check would be needed: driving at high speeds, bad weather, high traffic, or whatever which might cause you to perform less than your normal levels, you shouldn't call for a check.
You do not roll unless the PC is having to perform under stress of some kind, and failure is meaningful.
Skill based RPGs make this very clear. These kind of discussions about "huge margin of failures" for PC's in "everyday tasks" never really come up...
The Phb also tell that the DM call for a roll when the outcome is uncertain. If the DM consider the action obviously a success or an impossible thing, he can skip to ask for a roll.
In my opinion; the PHB and DMG set GM's up for failure here.
Yes, roll if the outcome is uncertain, but the base DC 10 is called "easy"... GM's are being sent contradictory messages on how to set task difficulty, and when to roll.
DC 10 should be - Standard acting under stress (SNAFU) roll. The basic roll when a PC has to perform on demand, yet there are factors that can cause them to fail. Your training should be enough for you to do it, but there are factors that can cause you to screw up.
DC 15 - Difficult - Acting under stress and there are other factors that makes the task harder. Only trained professionals can reliably pull this off...
DC 20 - Hard - The situation or obstacle is exceptionally difficult. Only a trained pro has a chance at success... Or you need to get lucky.
DC 25 - Only with great difficulty. A coin flip for even the most well trained adventurers.
DC 30 - May your gods be with you...
Etc.... This is all just off of the top of my head - in reality more thought needs to be put into this kind of delineation.
In my opinion; WotC D&D has had skill systems that have always had a tacked-on feel to their class/level based game, and they do a bad job of explaining how such skill systems should work in actual play.