Bus lanes have their uses, especially in somewhere like Bath where the traffic is horrendous. Our's locally, are spotless and regularly swept. Andy
There's better ways of "making progress" than sliding on your arse down one of Commandant Khan's diesel slicks.
I commuted into central London for 15 years. The ability to use bus lanes was (in my opinion) a huge improvement on both journey times and safety. Yes you had to share with buses and cyclists but it was easy to make progress. Compared with filtering down the outside (for from example Brixton to the Oval) with angry white van men coming the other way, cars pulling out of side roads and drivers turning right or just doing an unexpected U turn it was a joy. You still rode defensively but it was considerably safer.
As someone who was a London cyclist for years (and occasionally commuted in by motorcycle), I had zero problem sharing bus lanes between powered and pedal cycles. The real menace (as ever) was taxi drivers.