I literally cannot remember the last time I had to show proof of age to buy tobacco or alcohol. I'm middle aged - mid 40s, in fact - and places don't ask.
If I order alcohol, the reason I'm showing ID is to prove that yes, it was me that ordered it instead of someone else (and I'm showing my ID at the liquor store).
I've only bought porn twice - once a video and once a magazine full of naked men. I didn't get carded either time and this was back in the 90s. One of those times, I was 17.
And if I needed to verify ID online (for payments, etc), I have a secure way of doing that, which folks in these states simply do not have. The websites don't need to keep any information on file either. And this is the very thing that pornhub is objecting to. If they were rolling out age verification that already has some of this in place, it'd be a different story.
And a sidenote: I don't think it is all that wrong for a 17 year old to see what naked people look like. The rest of us need to be mature enough to make sure that young folks have a reasonable view of porn, including things like 'this isn't realistic and physically difficult for these reasons." A lot of so-called 'harm' is simply that we - the adults in the room - haven't held up our end of teaching.