The RMT has all sorts of practices that are based on steam trains. We have the same in France. The early retirement (on a very good pension) is because one has to breath coal dust while shoveling and the smoke. Items like pay adjustments because you have to walk from a restroom to you 'place' of work.
Couple of years ago it came out that a French railway worker had been on leave for 4 yrs, on full pay, because they couldn't find a job at his level. So he just stayed home. The good conditions don't stop them striking, usually as a first move, rather than after negotiation.