The issue with the intermediate 'specific lanes' step is three-fold 1) those buses and trucks will still require a human driver for most of their journey for dealing with the non marked sections so there's not too much gained because you're still paying someone the whole time. 2) the infrastructure is useless without the vehicles and the added capability in the vehicles is useless without the infrastructure so there's a chicken and egg problem with getting either started. 3) On top of those unless the lanes are completely segregated the only real thing adding hardware to lanes adds is making lane keeping easier. If not you still need all the accident avoidance cameras/lidar on the car the same as you need on a more 'free range' auto.