Your comment does not make sense, because Chicago has a good bus/train transportation system...see link above. AND Los Angeles has a somewhat fair system....you can look that up online.
Trains/Trams/Buses work fine in America’s cities, maybe not in the distant suburbs. Dayton, Ohio electric trollies in 1940s ...Why don’t you research that, and you will find out how America missed the real answer to pubic transportation.
In city of Chicago itself, public transport system works ok.
There are lot of bus routes not far from each other.
However as you go further out into the suburbs, they fan out.
25 miles from city center, there are almost no bus routes or trains along the circumference. They all converge towards downtown Chicago.
For example if you wish to go from Downers Grove to Oak Lawn, there is absolutely nothing. You will need minimum 3 transfers to get there and 2+ hours.
The crux of the problem is Chicago area is a 40-45 mile radius circle from city center, 1/4 of which is of course Lake Michigan.