Of there is one city in the US that really should have a good transit system but doesn't, it's Milwaukee. It's the largest city in Wisconsin, has cheap land, and is right next to Chicago. It has so much potential to build out a transit system that could be interconnect with Chicago's and yet all it has is a very small streetcar loop
Louisville, Cincinnati and Columbus are also pretty high on the list of cities with a ton of transit potential and yet don’t have any good transit