Not really. They do it many times a day, depending on how long the ride is. When people take busses and cabs, they aren't needing parking nor contributing to traffic. If 15 people take a cab instead of driving in a day, that is 14 less cars on the road. This is the main point in general. The traffic with cabs is a bit different - you know how many cabs work on any given day (on average).

I guess you'd be shocked to learn that here, not only can taxis use bus lanes, but so can electric vehicles to help encourage better choices.

I live in a city where taxis can use the bus lane.

Pros - similar to an express lane (HOV free, single-occupant vehicles pay a toll) it's handy when you're the one who's running late and REALLY need to get somewhere quick.

Cons - Buses deal with taxi congestion, cyclists deal with maniacal taxi drivers.

More people using taxis - less cars parked in busy parts of city? Lobbying from taxi tycoons may or may not have influenced this.

Bus lanes are relatively empty most of the time. There're not that many taxis to slow down buses. Maybe not win-win, but nobody looses either. To be honest, this is first time I hear somebody complain about this rule. Feels kinda natural over there.