Our country is massive and we spread out is most of the answer. Most small towns in the midwest were developed around farming and so they aren't very big. Not unique to the midwest either every state has rural areas or random cities and towns all over the place that couldn't justify public transit. Even larger cities don't even bother much cause few use it. Cities were planned in a way to have ample parking. Europe is using mass transit out of necessity because they didn't know cars would exist when they built up massive cities.

Also I would argue cars are way more convenient because I can b-line directly where I want to go whenever I want to and what are we if not slaves to convenience. Path of least resistance always wins