I've been refused for having expired ID, despite the picture very obviously being me, and my age very obviously being well over the legal age.
My wife's been refused because apparently her federally issued citizenship card, with a photo that showed she was well over age wasn't apparently good enough.
I actually remember one time when i was fairly young, early 20's, I'd let my license expire because I wasn't driving and couldn't be bothered to renew it at the time. I got refused at the liquor store and there was an old guy behind me. He just started ranting at the cashier about how I'm obviously legal age and how you don't need a license to drink and all this stuff. The cashier actually relented and sold it to me after, but that old guy's rant always stuck with me since.
And, it's made me notice how more and more, it's not even about how old you are, it doesn't seem to be about protecting minors, it just seems to be a way of training people to provide ID any time regardless of the reason.