I find this quite interesting, too. It seems to be very common around here in Chicago-speak. My only guess is that it stems from the fact that many stores and restaurants were possessives, being named after a certain person/last name. There are many examples like this: McDonald's, Dominick's (local grocery), Arby's, Wickstrom's (local Swedish deli), etc. and the practice seems to translate to many places that obviously aren't meant to be possessives, hence Jewel's (local grocery) and then onto WDW (Boma's, 'Ohana's). I think I spend too much time thinking about linguistics and semantics!
