We don't have that here in this small town; however, when I used it years ago, they were very crowded; most of the time, I had to stand, and I never saw anyone give up a seat for anyone.
Ha ha, that's what public transport system is. But metros are much better. They are crowded of course, but they are the fastest way of transport in cities. If you go by road, it will take 3 times the time.
Some days, I feel this IS the Boston MBTA. The subway (Redline) seems to be standing room only some days, and it doesn't help matters since they've "upgraded" the subway cars to these new wider, hi-tech, computerized cars. Sure, there's lots of space to walk up and down the length of the car, but the seats are all hard plastic, uncomfortable (my butt slides toward the edge of the seat) and the seats are wider (I guess to accommodate overweight people better?)
I have witnessed people give up their prized seat for elderly people with canes and stuff, but if you're suffering invisibly, like I do with advanced plantar fascitiis, then you're SOL.