The British have been either 1) lucky; or 2) schedule & control trains adequately to minimize the potential of a crash. Note also that British freight equipment is usually NOT identical to US even if it comes from the same manufacturer - for some reason they like boxcabs among other things, which are lighter. And like the other European countries they don't run big, heavy, slow freights like we do - because of traffic demands their freights operate more like Amtrak trains. In all, not a really fair comparison.
The old heads here will probably correct me, but I suspect the only other places in the world where you have the mix of heavy freight and occasional passenger like we do here in N.America are in Australia, possibly Russia, and possibly China. Note also that in China most of the HST line (where the really lighweight stuff runs) is separate from the regular railroads, which of course is the way it has to be for performance reasons.
Interesting crash test video comparing conventional and "energy absorbing" cars: [
www.youtube.com]