@ac22e2cc @20976234 

Who killed the electric car also has a chapter about this.

Bus manufacturers, tyre companies and oil companies teamed up to off to take over the street cars from local government to save them money.   They would run the streecars  for a year or two, declare the routes were not profitable and put stinking bumpy buses on that noone enjoyed. 

Then the bus company would only buy its oil and tyres etc from the companies in the monopoly. 

 @ac22e2cc Hard to find, but Ride the Big Red Cars by Spencer Crump is the classic on the subject