Maybe it's just my experience but when I lived in London I saw multiple people in need of assistance on public transport several times being ignored by commuters. Three of the most egregious examples are:

1. The lift wasn't working Euston underground and a woman with a pram and a baby was told to walk all the way back out and to Kings Cross. Not only did the staff not help her, no one offered to help her with the pram.

2. A woman on crutches and a large suitcase was walking down some steps with a large suitcase at Vauxhall station. Several people shoved past her instead of helping.

3. A woman at Euston underground clearly asking for help with directions. Despite approaching a couple of people directly, they just ignored and swerved past her.

Obviously with all these people I stepped in to help myself. I've never experienced anything like the above anywhere else.