It need not be a black and white issue there. The potential exists for natural market forces to have been eroding the profitability of quality mass transit, with a later upshot in opportunistic, and somewhat conspiratorial automotive capitalists seeking to topple the old status quo and corner the market lending the dieing industry a "helping hand" to get into the grave faster.
EG, it is possible for both to be true.
This is what I was saying. They were dying because of market forces before the conspiracy began, but anyone who says that the market is a neutral disinterested agent not influenced by actors within or around it is a liar or a fool. The automobile industry was already killing efficient public transit by aggressively marketing widespread use of automobiles, among other things, for overuse in places where they obstructed and damaged infrastructure which was required and maintained by parties other than them.
It's not as if the auto industry in the U.S. hasn't been up to other shady shit. Back in the '70s multiple people developed carburetors that allowed cars to get in excess of 100 mpg, the major auto manufacturers intentionally blocked development. That's just the really impressive stuff, inventors have been trying to get high-efficiency ICE autos out on the market since the '50s. In the '40s and '50s the Fish Carburetor company manufactured in excess of 100,000 carburetors that had markedly better horsepower and mileage than industry standard, and they were driven out of business (among other ways) with stalling tactics to block sales that included RtSing their mailed parts.
There's been tons of journalistic work and research done over the years (never mind actual statements from industry execs) that indicate that the U.S. automobile industry continues to produce vehicles which are obscenely inefficient while blocking efforts to develop anything better. Hey, can't have people buying less gasoline, right?