yet for every 1 compliment sent to most companies (non railway) there are 10 complaints. People complain at anything yet rarely send in letters of praise.
Definitely. I suspect it's partially because members of the public whom staff have helped (especially beyond what's necessary) may suspect that staff could get into trouble for helping them.
I'd suggest the other part is because a good service is the perceived norm and most extra touches would be perceived as part of the expected service.