Lyft LIne, Uber Pool as you said are private, not a public resource. Buses serves more than 3 people. How many cars would it take to match the number of people on buses ?
The red lanes are meant to be used to increase speed on MUNI buses.
Taxis are private but are regulated by the City of SF which includes how many can be on the road. SF has been trying to regulate Uber and Lyft but they are resisting. As for reducing congestion, Lyft and Uber adds 45k cars to traffic. Some says there aren't 45k in SF. Uber, Lyft knows but aren't sharing records. Maybe it's because they know they are causing congestion and don't care. Granted, maybe not all 45k are doing Lyft Lines, Uber Pool. How many are ? There's no transparency.
This is a non starter until there is transparency, cooperation, regulation by the local authorities.