Not that this wasn't racism, but if you are going to request ID for a product, don't put an age limit. Don't make the poor clerks have to decide that crap.
It's extra awkward when you accidentally tell the customer why you didn't card them. They'll say "hey, why didn't you card me?" And you can't respond with "we only card if you look like you're under xx" cause that'll send them straight to the burn ward