Well I'm finding this thread quite interesting.

Recently I was on a plant flight at the end of the day, and the plane was full full full. I had tried to book an aisle seat, but plane was so full, no luck. I'm large - tall with long legs to start with, but also overweight so plane seats are on the cosy side. Much cozier than if I was a small person with a proportional degree of overweight.

Anyway, I was all settled in when my window seat companion arrived. He had no arms. He was also tall with long legs. He then had to get himself seated and searbelt done up, which involved his not very flexible prosthetic hand and also his toes, ie pulling his legs up into the hand/arm zone. So, for as much as I was encroaching on his space, he was also in mine.

We both tried to be polite and accommodating, but we were both uncomfortable. In the plane we had no choice. In a train there is - but is raises an important question: whose suffering outweighs the other persons? Who has the greatest claim to space and comfort? Is it the man with no arms (because presumably he had no choice in that)? Or is it the person who through genetics was already larger to start with? Or is the person who is experiencing the highest degree of pain? What if the man with no arms enjoys a higher degree of health and functioning than the fat person, who has a chronic disease?

Off on a bit of a tangent there, but my own opinion is we all have an equal right to comfort, regardless of our situation. I personally think what was at fault here was the design of the public transport, and it's failure to accommodate many needs.