Any widespread transportation overhaul in America would quite literally involve dragging stubborn rich idiots out of their suburban mansions

I don't think that would be necessary. Running utility lines to low-density areas is really expensive. Take out the subsidies or privatize exurban utilities altogether, and there would end up being a strong disincentive to live there. And due to the nature of sprawl, most of these suburban and exurban houses bottleneck around one collector road, and that collector road probably goes over a few culverts. They functionally depend on grocery stores and gas stations that are usually several miles away. All it would take is to [redacted] a few points at once, and an entire bedroom community would become unliveable. They'd end up getting in their SUVs and tearing up each other's lawns to try to get out. At that point they could either relocate closer to resources, or cling to the necrosis and go down with it. These asphalt and vinyl and particle-board and monocrop grass landscapes are so close to collapsing; all they need is a little nudge.