If I end up eating at the Boathouse I'll be wearing a collared golf shirt and some khaki shorts. I can't control what everyone else wears, but better to be part of the solution than part of the problem
I don't think it's necessarily the average guest you are pointing out. I don't deny that those people do exist, but I still think they are outliers. I bet if you go to the Boathouse on a busy Saturday night less than 5% of the customers will be dressed in tank tops and flip flops with their underwear hanging out. The average customer will probably be wearing something at least half nice and there will likely be a decent number of guests in jackets. I think the average guest knows better than to show up at a nice restaurant dressed like that. Now if you are talking just guests in general at the theme parks then the number of the lesser dressed will probably be higher.