we do also travel a lot more miles since 1 mile is 1.6 kilmeters.
but in terms of deaths per mile traveled, US is not quite so far off, 7 to 3. still more than double but not an order of magnitude. I do think it's a little unfair a comparison though because the US is so different is spread and design of cities, wayyyy more sprawled, i mean most ouf our growth epecially around cities has been since the advent of cars and freeways. Not advocating it, but it's a very different type of driving. Maybe mexico or canada is a better near-comparison vs old world tight city/town centers.
also we drive way bigger cars. and theyre getting bigger. even the "tiny" cars here like the mini had to come out with bigger versions cuz america. I mean, it's happening everywhere, people want bigger cars everywhere