I've never seen that enforced. There are some local family pizza places that have a machine or 2 and kids play them all the time. Same at the bowling ally. I own a restaurant/pub that has 5 machines, but I don't have a lot of kids in there.
If you are in Columbia, SC and want to play some pins check out my spot. www.reddoortavern.net .
I have SM, Metallica Pro, FGY, Monopoly, and TSPP currently.