Where has this actually worked? Around here we have empty buses that stop 10 feet after every traffic light just so they can snarl up traffic. They have their own, private lane on a couple of roads. So 33% of our congested roads are empty, except for the occasional empty bus.
These monstrosities constantly change lanes without signalling, which is to be expected since they own the roads. They stink, and they are safety hazards because everyone is trying to squeeze into the lane they are not currently occupying.
It is wasteful of money, both "public" (i.e. already confiscated by the govt) and "private" (wasted fuel).
Many cities have well planned, highly utilized mass transit systems.
However, I agree that special HOV lanes or reserved bus lanes are asinine and don't work. Those are usually minimum cost, chintzy attempts to DO SOMETHING BUT DONT SPEND ANY MONEY. If your town's system is screwed up, its because you got what you paid for.