It's not really a question of what PH would want, but what the states will accept. The government isn't going to provide an age identification program, because

It's not really a question of what PH would want, but what the states will accept. The government isn't going to provide an age identification program, because they really don't want to enable people to watch porn. This isn't about protecting the kiddies; it's about keeping porn out entirely. And PornHub knows perfectly well that nothing they do will satisfy a state prosecutor looking to harass them. Even if they collected photo IDs, police will set up a sting with fake IDs. So they give the government what it wants. They leave. As you said, anybody with a VPN gets their porn just fine, but the government cares more about the perception of morality than actual morality.