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.

This reminds me (fondly) of the Caribbean.

GP commenters is missing out that this is usually a culture-wide expectation.

If you're 30 minutes late, you mention the bus, and your boss gives you a knowing smile. Because it happens to him too.

Efficient? Less so. More relaxed? God yes.

Exactly, the work ethic is definitely different in South America (grew up there)