You may be really surprised how crashworthy modern design EMUs are. Im fact, vehicles following the newest UIC crashworthiness standards protect people inside the train better than any kind of AAR-compliant vehicle.

Grade crossing protection… First, road vehicles have no business on a grade crossing when a train is near. Period. And you can be sure that the road vehicle will lose in any case. Rear-end and head end collisions are, unless within station or yard perimeter simply a sigh of insufficient signalling systems. Within station/yard perimeter, speeds are low enough for the energy absorbent elements to work. And if those elements did their work, they can be (relatively) easily replaced.