Now we all make assumptions. We see a small child in a mall and we assume a parent is quite near. We see a black cloud in the sky and we assume it is going to rain. These are pretty normal assumptions that we all make from time to time. Where it gets a little tricky is when we see someone with a disability. The assumptions people tend to make are based on their past experiences in similar circumstances. For instance, if the last time you dealt with someone in a wheelchair they were pushy, demanding and bitter, you might get the idea that all people in chairs are like that. It might even be subconscious. If you have run into several people with the same attitude problem then your original assumption becomes confirmed.
People are the same everywhere. Some people are bitter and unlikeable. Some people get cranky when they are having a bad day. Some people take offence when they get caught doing something illegal or immoral. Some people judge a group based on a mere sampling. It is like saying all apples are rotten because there was one on the bottom that was bad.
There are people in the world that will not tolerate others who are different from themselves. There are people in the world I do not like. I do not find them likeable. That does not mean that I judge all people who have similar attributes the same way. People need to be judged not on assumptions but on individual experiences. If you see someone in a wheelchair treat them like you would any other individual. Oh and keep your toes out of the way, they may be having a bad day.