I wear a "Please offer me a seat" badge as I can't stand that comfortably (leg joint damage) for daily commuting. It mostly works ... but I wear it to try and avoid having to ask out loud because it's obvious. Trains are better than the tube usually but can confirm there is a tragic rate of selective illiteracy on both when confronted with either a POMAS or BOB badge. Particularly amongst fit looking young men in cycling gear who still let their eyes roam the carriage a bit.
I'm usually not going long distances on the tube so I often do stand if it's busy as I do a shortish journey and by the time I've fought to the seats if it's busy, I then have to run a gauntlet to get off - after being ignored anyway. I also sometimes decline kind offers on there if I'm having a good day, explaining that it's ok but I'm only going 1 or two stops and that the badge is more for my longer train commute. I always thank people though. They definitely ignore pregnant women more than me, although after my accident, when I was still using a stick and had a visible limp I had an older gent look me up and down with visible disgust when he had to let me sit in the window seat next to him on the bus. Walking aids are NOT exclusive to the elderly!
Some people are unbelievable. I had a man (standing) give me a sickly sweet smile and patronisingly ask me to kindly give up my seat for a pregnant woman, with my POMAS badge on display. I declined but suggested he ask anyone in the carriage NOT wearing one, like the man sat next to me. My seat mate was a giant of man. I think the asker found him intimidating next to the little blonde lady!
I've had someone ask for my seat and the one of the lady next to me on the train so she and her 9-10 year old Dd could sit and do the kids morning hair routine on the way to school. I refused - badged, and the lady next to me (by the window) was getting off at the next stop shortly and said they could have her seat when she stood. I semi-stood up briefly before then to do something- probably readjust my clothes and nearly sat down on the kid . Her mum had tried to slide her in behind me. I did snap at them.
Travelling on a packed skeleton service on a strike day is the worst. If you're not on at the start, you will not get a seat. I've been visibly badged, squashed against the window with a bike handle practically trying to enter me whilst a happy man in lycra centimetres away has stretched out as much as possible and smiled jauntily right at me as he looked round the carriage and went back to his phone to read. The badge makes it very apparent that I need a seat. I shouldn't have to ask on top.
Ive seen a tall man get on an SWR service pushing a very little girl in a tiny wheelchair. It was a hot day, fairly busy service, he looked tired and he was obviously having to really bend to deal with the chair- his poor back. Two cyclists had the seats next to the wheel chair/buggy/bike area, with their bikes, having a nice chat. These seats are near the doors and marked priority. Tired man and I were stood right in front of them and they clocked us and then deliberately only looked right at each other (bar the odd side eye to see if we'd gone) for ages until I said something. I know we have voices but we also have eyes and brains. I also know that not all disabilities or needs are apparent but I am prepared to be told that.