Kit - I agree with a lot of what you said.
Discrimination is something we'll always have on Earth as long as there are humans. That doesn't mean we have to accept it. Things are better for the disabled than they were in the 1960's and earlier. I think the disabled were pushed aside with the Industrial Revolution. Before then, if a disabled person survived the disabling accident or birth event the family often found chores or jobs for them to do. Someone with developmental disabilities could feed the chicken, draw water and other simple farm chores. If you were a tradesman the handicapped could do some of the simpler tasks of the trade in many cases. It wasn't an ideal situation back then, but it was better than life in the recent past.
Some of what you're saying as a negative (being on time) is something that would be required of any worker. If the employees are being bussed to the job, the van needs to leave at a certain time. If the employees meet at the job site, they should be on time so the manager can make announcements, see that equipment is handed out at the same time, etc. Not different from when I worked and we had to carpool to the distant worksite. If you weren't there by the designated departure time then you drove to the site at your own expense. Reasonable because you didn't want professional staggering into the work site at different times.