Japan doesn't use road salt,
Correct. In Niigata prefecture for example they use WATER from zillions of nozzles placed at the center (crown) of the roadway. They are also designed to act as don't-cross-the-median bumps with little reflectors. Of course, this only works above freezing and in times of year when humidity is low.
Different cultures do different things in different climates. Also, some people may have chosen to replace cars more often in exchange for being able to have wet-road traction, as opposed to sand over snow traction, for more hours of the year. What works in the Cascades may not work off the coast of Maine (wet, soggy slushy show that builds up to 8" and then the top 1/2" freezes into a crust, for instance.) Again, the desired effect wasn't just traction, but chemical removal of many inches of snow and leaving a residual on the road so that flakes from the NEXT storm would turn to water for a little while longer before accumulating.
Yes it did turn many cars into prematurely-aged rust buckets - I remember pushing my finger through the floorboards of my uncle's old 220D Benz - the steel had corroded just like flaky croissant. We used the hole to drop M80s out of when passing through tunnels - they sounded AWEsome...
It was also hell on mufflers (heat accelerates corrosion) and muffler brackets. Hey but different people choose different trade-offs in different places; here the choice is body panels that last longer, plus enviro-weenie concerns in exchange for more 'stupid' accidents and more chipped windshields. Including a higher human toll in the form of injuries to drivers, passangers, and maybe a 5-year-old in a crosswalk who gets bumped off like a flippered pinball because someone in a Suburb-a-saur SUV couldn't stop in time.
Maybe the Nature Conservancy, Greenpeace and the Sierra Club take kickbacks form the body shops for all the extra work they get? <-Joke