A big reason US trains are not is efficient is because the US is nuts about safety. Thus US trains are often twice as heavy as European trains in order to make them crash worthy. There are probably many more road-level railway crossings in the US than in Europe. Still, the US is way more strict, and I don't know how effective that really is at preventing accidents. Surely it must lengthen the stopping distance, which would be safer if it could be shorter.