Speaking as a big fan and avid user of public transit, I say: not gonna happen in many places.

Public transit works in densely populated areas, like in NYC where I live. Digging and operating a tunnel costs a lot, and only pays for itself if you can run many trains with many passengers, who live close enough to their nearest station. Buses are less expensive (though still are expensive), and require a driver per 50-100 passengers, not per 2000.

As long as many people prefer to live in suburbia (which may technically be considered a part of a city, like in Houston), they are going to use cars (or technically trucks), because it's the most economical way to get around. As long as the destination of their travel is not an utterly dense area that does not require a car (like commuting from NJ to lower Manhattan), people won't leave their cars mid-way and change for a train or a bus.

It's not the car lobby. It's people wanting to live quite separately from their neighbors, in detached houses that they fully own. Or maybe cities that enforce low density for a number of reasons (mostly NIMBYs who want to keep the price of their house and land high).

Suburbs are dense enough to support transit as proven in a small number of cities around the world (mostly not English speaking). However suburbs can only support great transit, since anything less and driving is enough better as to be worth it.

NYC has a real cost problem. Digging a tunnel costs a lot - not anywhere near what it costs in NYC. You can also build bridges over the top for a lot less than digging a tunnel. Modern subways should be 100% automated saving the cost of a driver. (I keep hoping we see self driving buses since drivers are the large share of the costs)