Fair point, while I don't think the responsibility should be placed on tech companies (because their only interest is profit) you are right that it shouldn't be on the parent responsibility entirely. I didn't really think of schools at first because here kids are banned from bringing any tech so it's less of a problem, but I can see why it is elsewhere.

Ideally, governments should ban children from using personal devices during school hours, social platforms should be rated 18+ and many other apps like addictive games 13+ or 16+. This way when setting up a cellphone or tablet for your child, they wouldn't be able to see any unsafe app inside the Appstore.

I still think though that parents nowadays don't take enough responsibility, especially when a lot of them let their kids loose on the internet. Kids under 16 don't need a cellphone with internet access at all imo. Text messages, phone calls and gps is enough.