It's hard to say with such a short description, but as i read it, the google car never left its lane, just moved right to the edge of it's lane to avoid some debris.
Why did the bus move into an occupied lane?!?
Why did the bus move into an occupied lane?!?
It depends on the city, but bus drivers often don't care whatsoever about other vehicles in the way. They merge and let others avoid contact.
Because that's what busses do all the time, whether or not that is safe, legal, or desirable.