Right, but from the perspective of the bus rider, it's still unavoidable, as the rider can't control the bus driver. So I'd say it's still an acceptable excuse to give at the client meeting, unless there are other, more timely methods of transportation that you could reasonably be expected to take.

In places where this is sort of thing is common, I wonder if people aren't bothered by it because they truly in their heart of hearts don't mind, or because they've just resigned themselves to the unpredictability of their transportation.