I get the origins but I simply don't believe it can be done effectively throughout the Midwest. There are some short routes that work within the urban core of a few cities but by and large the downtowns of the cities in this region simply aren't big and healthy enough yet to support it, and nowhere even close enough to justify people getting rid of their cars.
What would actually work better for me in Ohio, and what is in the works, is regional train lines like the Brightline in Miami. It's extremely common for people to drive between Dayton, Cincy, Columbus, and Indy, all four of them all the time for everything from sports games to work commutes. Now that is an opportunity to gather a lot of ridership on a train, even though there is absolutely nothing in between these cities.
As for the Kei cars, I've got the problem of happily driving one around town here in Dayton, but also needing to drive hours on the freeway to those other cities quite often. Intracity rail would not help me at all in Dayton, but intercity rail to those other cities and their airports absolutely would, and would allow me to only own a cheap Kei car for local trips. Besides Chicago which has an urban core that rivals SF, Oakland, and SJ combined, no other city anywhere near me can support intracity commuter rail but could definitely handle intercity rail. Hell, the distance to connect all your Bay Area downtowns, from SF down to SJ back up to Richmond, is as long as the distance from downtown Cincy to Dayton to Columbus except your in a conspicuously dense suburb the entire time. The Miami Brightline runs the same distance as downtown Dayton to Columbus but it's deep in the Florida suburban hellscape for every inch of it. The Bay Area metro's density is over double that of Columbus, and half your counties are uninhabited mountain forest.
For the Midwest, its a problem of affordability. The density simply doesn't exist to cover the cost of intracity transit, but if we were able to complement intercity rail with inexpensive Kei cars that recipe could free up a lot of space and disposable income for many people.