Tunnels full of low-occupancy cars as a commuter alternative? I don't see much of anything in here about accidents/safety/emergency response. All of those things seem much harder in a "bunch of Model 3s in a tunnel doing point-to-point travel" world than in a Subway world, while also more likely to be needed, because you've got so many more vehicles sharing the space. Seems like a very important not-considered expense.

"The cost of loop stations is so cheap that you can place them next to any number of desirable locations."

This also feels wildly handwavey. You need a LOT of them if you want this to be a viable point to point network vs just a higher-risk way to build a subway. With individual vehicles going to individual stations at user request, too, we seem to have brought in "full autonomous driving" as a prereq.