Rather than government dictated internet controls, there needs to be better systems and education in place for parents to control what their kids can access. Service providers, operating systems and tech companies need to be better at helping parents - especially less tech savvy parents manage this part of their family life.
You can talk about better sex education in schools but kids are still going to do things they think they can get away with. Good parents don't let their kids have unfettered access to the real world so should they have unfettered access to the internet which can obviously be just as dangerous in so many ways.
There are too many sites to simply expect parents to have the bad ones blocked - it should be an opt in system for children. As a parent who pays for the devices and services, they should have complete control over what their kids can access and the same way a kid would come and ask for permission to go out to so and sos house, or go to a particular party or night out, they should ask for access to a particular website, app, forum etc. The parent then has the responsibility of looking into the content and making a decision on whether or not it's suitable.
There should be simple, well presented data available to the bill payer, which breaks down internet usage, app usage, time per site/app/user etc so parents can easily identify trends, habits and problems before they become too serious. This is all possible now for those of us who are tech savvy enough to implement it but it needs to be offered in a well designed, simple and intuitive interface marketed at parents and government needs to invest time and money in advertising and educating adults who are often lightyears behind their children when it comes to understanding the technology and online offerings in their homes.