@tk @baralheia You're many kinds of right. I fervently wish US regs weren't deliberately configured to cater to the market-control preferences of the American automakers (+ those international ones who pay the steep cover charge to participate in this market), at the expense of things like pedestrian safety (and many other kinds) and on-road fleet fuel economy, but that's the fetid reality we live with here on the North American regulatory island of Ferenginar.
There's also more nuance and complexity to it, though. Road and traffic conditions in Japan really are significantly different to those in North America in ways that heavily affect the practical safety of a Kei truck. That would still be the case even if LHD Kei trucks were a thing, and the fact that privately-imported Keis are RHD makes them significantly more unsafe and incompatible with North American traffic.
Some states and provinces are now refusing to register Japanese-specification vehicles imported under the 25-year-old cutoff exempting imported vehicles from US safety standards, the 21-year cutoff for US emissions standards, and the 15-year rule for Canadian safety and emissions standards. That really is a sound decision by those states and provinces, bitter though it be for those who think a Kei truck best meets their needs.
It also sucks that the Australian-type "ute" (formally "coupé utility", a station wagon but with a truck bed instead of enclosed rear cabin + wayback) withered and died in North America after the Chev El Camino and Ford Ranchero went away by the late '70s, as nudge/wink CAFE regulations spurred automakers to pivot to trucks and truck-based SUVs (and miscategorize certain cars as "trucks"). A ute would much better, more safely, and more economically serve a great many North Americans' needs than the F-990 Super Duty King Ranch Canyonero types they're more or less forced into. Subaru's Baja was a more recent halfassed effort at at ute, but as a 4-door its bed was too small to be useful for more than Harry Homeowner's smaller pickups at the garden centre.