Yes they can. I never went over to any friends house until my mother met their parents, strict rule harshly enforced. And all TV use was heavily controlled by my mother. That's what raising a kid is all about. And I was a latchkey kid, but there were rules, and I got checked-up on. I wouldn't let a kid play GTA and any parent that does is a flaming moron, but that doesn't mean adults shouldn't be allowed to. Attempts to reduce reality to PG-13 to make it "safe" for kids that aren't actually being raised by their parents are doomed to failure and deserve ridicule.
Is that the norm for latchkey and single parent kids these days ? Gangs, crank, etc... That is the threat for most single and latchkey parents, not libertarian nostrums about 'censorship' or 'nanny state'. And it's getting worse.
Look, if you libertarians want us to become like Holland, well fine. Most Americans don't and they put GWB back in the White House.