Bus drivers in the Bay Area are notorious for ignoring traffic (and pedestrians). Apparently there is some indemnity or statutes that make suing either the transportation agency or the driver nearly impossible and so pretty quickly people learn that the bus drivers drive with impunity. Plenty of stories posted to the local traffic column in the paper, and shared amongst neighbors and in the department of safety's "blotter" feature.
Google needs to go back and program their cars to always assume that buses are out to get them and avoid them at all cost, They are an active traffic hazard often operated by a disinterested and distracted driver. The only way to "win" is to not be where ever the bus is.