Said parents and guardians cannot protect their kids all the time - they have their own responsibilities like work. Most kids go to school during the day. The few that aren't grow up in homeschooling systems or cult-like environments, which are their own problem.

I frequently see this rhetoric (parents should look after their kids) from naive people on the internet that clearly don't have kids of their own (or don't have teenagers, or don't live or let their kids live free, etc)