I will say that I don’t live in the UK, so maybe it works differently. I’m assuming internet plans include some kind of service contract you have to sign, and minors can’t legally sign contracts without parental consent. So every internet connection is the responsibility of the adult who did sign it. If kids are going to be using it then it is their responsibility to put parental controls on their network and devices.

But like the other response said, its not actually about protecting kids. Basically, if a politician ever says those words, its almost certainly an attempt to take away freedom.