First of all, I happen to have a transit ID card that signifies I am qualified to use red tickets. I am legally blind—even though it might not be obvious because my eyes look normal and I don't use a white cane. Many people don't realize it, but there is a whole spectrum of visual impairment and blindness. Regardless, the whole point of having the ID is to serve as proof of one's eligibility to pay a reduced fare. End of story. Furthermore, when you browse the overall list of medical conditions that qualify individuals to obtain a transit ID, many of them won't be discernable to the casual observer. Do you think you can tell at a glance that someone has a heart condition? How about a hearing disability? Epilepsy? Or symptomatic HIV infection?
That's exactly why it is not supposed to be up to some improperly trained yahoo to make such judgments based solely on appearances—nor is it acceptable for said yahoo to throw out misaligned accusations at members of the general public. I told this guy I had an ID, and he said something lame about how I'm supposed to show it when I come through. If that really is the case, they've sure been doing a rotten job of enforcing this policy in the two years or so that I've been riding BART because I've never before been asked to do so. Had this station agent nicely requested to see my ID instead of confronting me in such a wildly inappropriate manner, I wouldn't have had to submit a complaint letter to BART. I don't know if anything will come of it, but I can only hope that someone gets the message and takes a good look at BART's flawed customer service procedures and lack of sensitivity to riders with disabilities.
Honestly, I think the more serious problem on their end is the fact that you don't need to provide an ID to buy red tickets. BART should revise this process if they want to reduce the chance of random losers fraudulently purchasing and using reduced fare tickets. And if the imposed penalty really is going to involve what only amounts to a stern order to go out and buy a full-priced ticket, it's hardly a deterrent to those intent on cheating their way out of paying full price.