These systems won’t work any better than identification requirements for alcohol and tobacco or anything else. Maybe you didn’t know anyone who drank or smoked when you were a teenager but they are pretty widespread even when parents aren’t negligent. Systems like the proposed ones will be even easier for kids to find a way around.
I’m somewhat in favour of these foolish attempts at control because they always drive innovation in technology to circumvent them and adoption of that technology creating a thriving underground scene. Content piracy and alternative platforms could use a resurgence and this is just the thing to get it jumpstarted.
I agree that the recent craze about internet ID checks are foolish but your example falls on its face. ID checks to purchase goods at a physical location are actually quite effective. They don't achieve perfect compliance but that's not a fatal flaw (or even necessarily any flaw at all despite what people might say).