If you really need to understand why car companies will not take your advice, you should look at their sales numbers. Car companies don't sell many cars in Montana. They sell a lot of cars in urban concrete jungles and suburbs like those that exist in California and basically every major city. Solve one major city (especially one with hills like San Francisco), and you've likely solved most major cities, worldwide.
California has 14.5 million cars registered and 2 million new cars are sold in the state each year. There aren't even 14.5 million people in Montana. It's an incredibly easy market to "disrupt" as it were, and they have people in California that are known early adopters to lean on for buying, testing and validating their product. The people of countryside and similar locales are recalcitrant and will see products like these as extraneous, "taking their jobs" and "killing their freedom of driving."
So once they've tackled the low hanging fruit market of California, maybe they might consider expanding into the harsher wilds. But, similar to public transit, the infrastructure worth investing in is infrastructure most people will use, and unfortunately that is not a self-driving Ford F-150.
Signed, Common Business Sense.