Ours used to demand a supervisor override for a typed-in date, but then about 3 months ago that part vanished. I still scan whenever possible (note, SCO has not allowed me to scan, and I haven't tried again recently). I've never had a guest question why I scan rather than type it in.
Amusingly, I had one guest ask to see MY ID to prove that I was old enough to process the transaction. And yes, I immediately reached into my pocket for my wallet. When he saw me do that with no hesitation, though, he demurred. My guess is that he was law enforcement, we do know that many local towns run undercover stings to see if we're checking guest IDs. If I had shown any resistance, he might have pushed the issue.