Does ANYBODY EVER provide an accurate response to a question like that (except when there's reason to believe they can detect it and do something to your detriment if you lie)? If so, why? Anybody who asks deserves to be chaffed into oblivion with garbage data. Especially, who would be dumb enough to admit to being under 18, or, worse, under 13? An 8 year old should see the obvious reasons not to do that. A bright 6…
Have you ever given the wrong information, and then later needed to use it as some type of security / identity verification? I know I've run into it at least once, I think maybe Microsoft, where having an unknown birth date on the account became a huge headache. Lesson learned. Write stuff like this down in a vault too.
I gave Google an off-by-one birth date way back when. A few years ago they figured it out -- sorry, don't recall what hints they may have been working from -- and demanded a correction. After considering the implicit threat, account termination, I surrendered the actual birthdate.