In addition to what others have said, I would argue that both cars and suburbs (which go hand-in-hand) atomize society and divide people from one another, while trains and dense cities are both pro-social. This may not have been intentional, but it nevertheless plays into the hand of the ruling class by preventing social socidarity.

The single family home in the suburbs trains the homeowner to behave as the lord of their little manor - neighbours are at best an unwelcome intrusion into this manorial fantasy (good fences make good neighbours), and at worst are petty enemies, whose housekeeping, yardkeeping, or decoration could affect my property value. Apartment living doesn’t have any shortage of potential problems with neighbours, of course, but they’re the ordinary interpersonal issues rather than bourgeois concerns about investments and property values.

Suburban living also trains the homeowner to be suspicious of any passers-by, as they could be potential enemies. Are they supposed to be here? Are they causing trouble? Vandals? Casing out targets for home invasions? When you’re the lord of your little manor, any outsiders walking the street are a potential army of marauders looking to sack and pillage. Trayvon Martin was murdered for walking around in the wrong neighbourhood, and his killer was acquitted - after all, why was he there? He looked (i.e. black) like he didn’t belong. Every suburban homeowner has an internet-connected doorbell camera, enabling them to keep watch for potential invaders, and that footage as a matter of course feeds directly into the surveillance panopticon.

Cars work in roughly the same way, in that they’re a little living room that you drive around town. An isolated purely private space into which any kind of intrusion is unwelcome at best and an attack at worst. All the other cars, despite being driven by other people, are faceless things which are once again an annoyance at best (they’re in your way, preventing you from driving at the speed you want) or a threat at worst, and since they’re multi-ton steel machines being driven by fellow self-centred suburban assholes like yourself, they literally are a threat. Every other person on the road could potentially kill you due to carelessness or malice. This promotes an atmosphere of pervasive distrust in which everyone else is an opponent of some kind - either an obstacle or actively hostile.

Cars and suburbs act synergistically to suppress community and social solidarity. You live in your isolated manor and pilot your carriage to your destinations, all the while insulated from the ouside world and from other people. Anything outside the car is not your problem so long as it doesn’t come back to your castle, so any time you see the rot in the poorer neighbourhoods of the inner city you only hope that it stays contained and your neighbourhood stays isolated. Public transit, especially mass transit via light rail, is therefore a potential disease vector for them to enter your neighbourhood. It must therefore be opposed.

Bullet trains are of course not light rail and don’t enable the poors to invade the suburbs, but to the suburban subject, it is still unwelcome - it wastes their tax dollars which could be better spent for them on their private affairs - the manor, the car, and other toys. Overall societal benefit is after all not a concern, the concern is with the private sphere.