1. Dedicated bus lanes (speed, predictability).
2. Traffic light priority ( speed, predictability).
How many US cities implement even one of those?
I don't care how long it takes to get off the bus nearly as much as I care how long it takes to get on.
Separately, the variability problem can be somewhat solved with the real-time location updates that many agencies provide. You'll still have to wait the same amount of time, but some of it can be done comfortably in your house when the bus is running late.