And if it's not the same infrastructure, we can lower the fuel cost by reducing rolling resistance by switching to steel wheels on steel tracks, and then since no other vehicles will be on this infrastructure, we can chain multiple of the trailers together, aaaand we've invented trains.

All transportation alternatives converge into trains over time, it's like carcinization but for transport.

If we had dedicated infrastructure we could make the roadways out of wear resistant material. Maybe a metal or something

Such dedicated infrastructure lanes would cost an enormous amount of money, which the operators of such autonomous vehicles are not going to want to pay.

The whole point of self-driving vehicles is that they can can run on existing infrastructure, so that's a non-starter.

So... train tracks?