I know what you mean. I never understood why my Dad always seemed so grumpy when we'd be out and someone would try and help him (he used a walker). Now I know. A hostess in a restaurant tried to take his walker from him while he was getting situated in his chair....he was still using it for balance and help getting into the booth. She had no idea and grabbed it from him so it could be put behind the counter. OMG - if I could have melted into the floor I would have right then!! He snapped at her (loudly) and told her that when he was ready for his walker to be put away he'd let her know.
It seems that when I need help I have to look for it. When I don't need (or want) help there's a line forming of people ready and willing to do it quicker and better than I can.
I try very hard to be gracious and appreciative of these kind folks.....it's better than the alternative!! But, it's taught me to be much more sensitive to other people's boundaries. I no longer assume that just because someone is in a wheelchair or using a mobility device that they automatically need help.