NannyJan53
This happens on buses often too. I have seen people politely ask someone to move their bag so they could sit down. The 'offender' usually looks quite surprised.
I boarded a bus recently with Mum (93) it was full mainly of school children. Not one offered her a seat. Then a man got up and offered her his seat. I said in a loud voice, 'Mum this gentleman has offered you his seat' Not a flicker from any of the other passengers as they were all engrossed on their phones. I stood all the way to town!
I usually ask people to move their bags or move across if there is an empty seat next to them. They always do. I'm often travelling with my two young GC on the way to school and normally get them to sit in the space, at which point I'm often offered a seat close by. It is usually not people of white British backgroound who offer seats, we natives seem to have lost our manners.
A very nasty white British woman, smartly dressed and in her 60s forced her way onto a bus in front of me the other day, almost knocking my GD over as I struggled to keep my GS on his feet. I had words with her on the bus about queues and manners and many people on the bus smiled at me as I sat down. She was typical of the people with this behaviour I'm afraid.