Rural areas off the grid usually have some way of getting their own electricity, like solar or small hydro. These places typically also lack roads so Tesla charging isn’t much of an issue.
America is greater than 80% urban, not as urban as Canada and Australia, but urban enough that even if rural dwellers had vastly different electric resources, there would still be a huge market for EVs. If anything, urban users have a disadvantage because many of them don’t have their own parking in residence to charge overnight, which is not really a problem in rural America.