In multiple European cities now I see taxis being allowed to use the bus lane (while of course regular cars are not).

What's the policy justification for this?

Most cohntries Ive been to, that special lane is for public transportation including taxis.  Pushing the public to use more public transportation, getting to places fadter, save the environment.  I find it silly when I visit Poland and see people sitting in hours of traffic with just 1 person in the car.  Couldve took a bus and grt there in 15 mins.