Then I am REALLY surprised at the responses -- that people would have a "not my problem" attitude in the face of legislation and signage to the contrary! Wonder if the law is the same in NYC?
Perhaps the issue is that we are talking about different things (based this comment we might be). The legislation is only for the few priority seats (though the TTCs new streetcars and subways have more priority seats). There, yes, I've seen people "compelled" to give up the seat (though generally people are very good about giving up those seats (or not taking them at all)). I (and I think others) are talking about seats in general (not priority seats).
I'm also not sure how much "teeth" the bylaws have. How do they define "disability" and how can they prove someone doesn't have one? I've certainly never seen any law enforcement of it on the TTC (but I've never seen a situation where it was really warranted). I did find that the TTC has a webpage devoted to the issue, which is great.
https://www.ttc.ca/Riding_the_TTC/Frequently_Asked_Questions/Priority_Seating_FAQ1.jsp