one thing that really bothers me about my hero academia is the fact that aizawa threatened to expell midoriya on the spot during the first day of the school year because he couldn't control his quirk.
u.a. is a very flawed school of its own, but i feel as though aizawa should have at least read some type of files on the students to find out that midoriya had his quirk for a month so of course he wouldn't of have control over it.
but what bothers me the most is the fact that even if midoriya hadn't just gotten his quirk, its shouldn't of mattered. we know that people aren't allowed to use their quirks whenever they want. the only reason bakugou has such good control over his quirk in the beginning of the series is because he literally breaks the law.
so for people who didn't attend some type of hero school, didn't have anyone to train them, and don't have someone in their life (parent, guardian, etc.) with a similar quirk to guide them on theirs - it's basically impossible for them to have control over it. especially if it's a dangerous quirk where they can't just use it in their home in secret.