Are taxis/ubers really better for the environment than a personal car? I'm not sure I consider them "mass transit" since they still typically only carry 1-3 people. While they may require less parking infrastructure, they likely spend more time idling, and they don't reduce congestion on the road.

Some problems with buses are that they can be slow, require more planning, and may not drop you off exactly at your destination. There are three primary reasons people choose them anyway: Ethics (i.e. environmental concerns), convenience (in some cities, public transit is actually faster on average) and cost.

Bus lanes are meant to make buses more appealing by increasing their speed and reliability (i.e. convenience.) Filling a bus lane with Ubers will slow down buses, making them less attractive which also hurts the price conscious (i.e. lower class) the most.