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?

Taxis are seen as part of public transport. Letting them use bus lanes makes them quicker and more reliable, which can get more people to choose them over driving their own cars. I guess.

+100 🔥 FIRE added. Check your balance.

100% agree with you. Better use cab than personal car

Yes plus they pay a license and they’re supposed to use it only when transporting people