One of my coworkers once asked if I ever get stopped by BART workers because I don't look like I have a disability. Ah, that truly is the story of my life—but no, I've never been stopped. That's the funny thing about these tickets. You're supposed to have a specially issued transit ID (which I do carry in my wallet) in order to legitimately use them. Oddly enough, you don't seem to need the ID when buying the tickets. It makes me wonder how many sinister types have caught on to this fact and are unlawfully purchasing and using them.
Anyway, I've never been asked to show my ID in my travels, except for the couple of times when my ticket got demagnetized and I had no choice but to talk to an agent. On one of those occasions, the agent seemed sort of baffled, saying, "You're disabled?" Honestly, I do not need to justify myself to these people; I think they're supposed to ask to see your transit ID and leave it at that. My coworker pointed out that people have a lot of hidden disabilities these days, and it's true. I think various medical and learning diagnoses can qualify you to use the red tickets, although I don't know all of the specifics. Still, my incident with that ticket agent always crosses my mind whenever I enter or exit a BART gate. I feel somehow like I'm going to be accosted even though I'm not doing anything wrong. I've never been "quick on my feet," but I sometimes rewind that moment, revising my response. Instead of telling the agent straight out that I'm legally blind, my mind's version says something like, "You don't look stupid, and yet you are." That would probably get me in trouble in real life.