Perhaps they're used in the USA because, maybe, gaps between linked end units as in the photo above are common there? They don't seem common here, though obviously not unknown. It could also reflect the way the UK▸ disability laws work, ie that they don't prescribe standards which must be followed from design up but instead allow disabled individuals to sue an establishment for not making themselves accessible – this very rarely happens simply because most disabled people do not have the time, money, energy to pursue a legal case.
Eh? gaps between carriages within
MUs▸ are quite big enough to fall down, except perhaps on the new ones with wide gangways providing a continuous interior. I've commented before that
IETs▸ have particularly wide gaps at 1 m (nominal), but that may be more apparent than real. Their carriages have flat ends, while in an
HST▸ the end walls of the Mk IIIs taper quite a lot. So while the gap between body ends is 0.87 m, at the start of the corner curve I think it's 1 m or so. There may be a secondary factor in how big a hazard this is, depending on how far the doors are from the ends, but I'm not sure which way it would act.
As to attitudes to regulation, I don't think Americans are less litigious than we are! One difference I think is real, however, is in the use here of codes of practice rather than enforceable regulations. I know we tend to think of deregulation as the American way that we are copying (and Tory
MPs▸ are especially prone to think this), but if you go and look at the size of the Code of Federal Regulations you will find that's not true. Plus that's only the federal level, states and in some cases more local polities are at it too.
