I honestly wouldn't be surprised that part of the issue the Orlando parks have is that it's a Destination, so you end up with more tourists who get that little bit of extra courage to do stupid stuff they would never do back home. ("What happens in Orlando stays in Orlando" as it were.)
For a few people it could be because where they are from, at parks outside the US in some parts of the world it is acceptable to stand up on log flumes and rapids rides (at parks where there aren't seatbelts) so some people might not realize it is wrong.

) 
), or my personal favourite, climb from the back seat of a log to the front while it's moving along. There are so many children in particular who stand up for the ride and the parents don't do anything about it. (Ex-splash CP)