Because a lot pf parents dont give a shit. Their focus in life in getting home, eating dinner and watching NF all night.
They want schools and gov to act as free babysitting services. And if something screws up, instead of taking responsibility for their own child, they blame tech companies or gov or schools. Also doesnt help when some parents have dumbass kids getting in trouble too. I dont expect 6 year olds to know anything, but 16 year olds yes.
When my bro had kids old enough to use the net, they installed some kind of Net Nanny thing on the family PC. Cant be that hard. I bet most parents dont even do anything except tell them to dont search for porn. Next thing you know, parents Joe and Sally are busy watching Hulu leaving their kids to do whatever they want all night.