No matter how closely parents try to manage their children's lives they can't possibly protect them from life's trials and tribulations. Indeed, parents shouldn't protect their children from those things. Parents should guide their children instead in how to effectively manage the challenges they'll face on their own.
There is obviously a disparity between what you think 3-year-olds are capable of and what the other parents think kids this age can do. It would be useful to examine this, and think about whether you yourself were treated as less capable than you were by your parents, or if they gave you too much independence, making you resolve to be there for your own kids at all times.
Setting boundaries with our kids is a process. And we get to work at it with both imperfection and diligence. Regardless of where your parenting approach lies, seeking fellowship from other parents with similar goals -- especially those parents who are a little further along the parenting path is greatly beneficial
I hate homework because it brings out that side of me I swore I'd never be as a parent. It brings out nothing but ambivalence in me as I do the dance of balancing involvement or support with trying to teach my child accountability, autonomy and self-discipline while still have him excel in all that he does.