The government involved? What could possibly go wrong?
Meanwhile, I do remember a time, the 90's, when every Adult Themed website required a Credit Card. I could see it going back to that. That would be the most realistic solution to the problem.
So, what happened to requiring CCs? Without googling it for sure, I believe I read that one company came along and started buying up streaming sites. They then gave porn away for free, but introduced a subscription service for customers who wanted to pay for better stuff. Or something like that.
Breaking up a monopoly essentially.