HN users are not representative. Kei car enthusiasts are not representative. Americans love F-150s, Tacomas, Highlanders, 4runners, RAV4s, CRVs, etc. They by-and-large buy the largest car/truck they can afford. You look up the sales numbers for this stuff and there's just no contest; e.g., CRVs outsold Fits by almost a factor of 10. The marginal gain of "parking is slightly easier in streets or unlined lots" is something most people don't care enough about to buy a smaller vehicle. They prefer the other conveniences of large cars.
Is it true that manufacturers like selling larger cars because they have higher margins? Sure; they also like to sell you on the higher trim levels of small cars for the same reason. But Americans are happily making that easy for them.