In my experience doing home repair calls, they’re neglecting the environment they are living in. This isn’t unique to obese people but I’m sure it contributes strongly to their apathetic nature. So you’re likely right that the water is just splashing around and left to sit cause they aren’t agile enough or don’t care enough to take care of the environment they are living in.
You can make a wet bathroom, these are popular in Asian communities where the entire bathroom is a shower.