an extension to a) is also that there is non-trivial risk.
PII breaches require disclosure, and that's the last thing PH wants. There is also potential legal ramifications if they fail to handle the PII correctly and stuff gets leaked.
Then there is the risk that somehow a kid manages to get through anyway, and they face the risk on that angle -- angry parents and crusading politicians.
Furthermore, how are you verifying these? Actual human eyes? Image recognition for valid Utah driver's licenses? What if they live in Utah but are from out of state? Fake IDs are a thing, and if it's an uploaded image I could have easily whipped up something with Photoshop when I was like ~15. Compress the image a little to help mask any artifacts and then cry "potato quality phone camera" if anyone questions it.
Opens up a whole can of worms that don't make sense if you're trying to solve this on the scale of just one (1) state. Maybe if California, TX, and NY go in on it, too, but otherwise it's a lot of risk for little gain.