Should bigger people get special treatment?

This is not towards anyone with physical problems that make them gain weight or anything like that. It's not even about people who are a little over weight. I'm talking about people that are so bad they can barley walk. I'm talking about people that are bigger because they over eat, eat the wrong foods, and dont exercise. Should they get special treatment? A lot of them already do but I'm asking in your opinion should they? For example: if you're over weight you get to use the motorized carts, take the closer parking spots, get on disability etc . Why I'm asking this is because today I was on a public bus and a lady who was very very large was sitting where people with disabilities are supposed to sit. A blind man walks on the bus with his seeing eye dog and she didn't even offer her seat. She say there and he accidently touched her because he went to sit in the disabled seat and she was there so he had to struggle to find another seat. Now I don't know if she had some sort of disorder or if she was just big by choice but it really upset me that this person with an actual disorder wasn't allowed to sit in a spot designed for him because a person who was way overweight was there.