I just asked the ten year old next to me what 2 + 2 is, four.
The majority of underage users are 9-12, not pre-schoolers.
There are 10 year olds who you wouldn’t never suspect are underaged and 14 year olds who act completely underaged and are whiny little brats.
The solution is banning people who do things they aren’t supposed to do. If someone is harassing other users, ban them.