Japan still has a higher density of population and far less landmass to cover. My nearest neighbor is over a mile away. Are you going to build a bus route or light rail just for me? Or through county, state, and federal forest lands? Logistics is a bitch.
The issue is the complexity of the bespoke design of drive trains. It’s nigh on impossible to design a “one size fits all” or even “fits a majority” of solutions for a conversion kit that isn’t stupidly expensive.
See: Edison Motors. A Canadian heavy haul truck manufacturer startup that is trying to offer electric conversions for commercial light and medium duty trucks.