I'm gonna be the one with the unpopular opinion here. I personally believe they should have focused on expanding the Russian theme instead of trying to catch ATS buyers. That is what made Spintires so great, an original concept and setting compared to all the other driving simulation games. Plus there are a lot of promised things that still didn't make it into the game, like tracked vehicles which are still not officially supported, and with a new game coming next year it seems like they will never be.
As far i remember, American Wilds were annunced before Oregon (and its wood chain industry). More than tracks, a 64bit version of the game should be a better update. But who knows, maybe we'll got all those things (and a bit more power on trucks) with Mudrunner 2.
The american community is the second market buyer of Mudrunner, both dev and publisher were more focus logically on this target (most of recon cars are american). American trucks aren't made for off-road, but they go more often than you think in reality (even a lot more in Australia) on really dangerous tracks.
Second, russian industries doesn't give official licenses, on that side is more restricted. Spintires got the right truck fender grill, Mudrunner got the fictional ones. So that's why we got Murica and not Mother Russia.