The 'few months' bit doesn't seem quite right - the cost to get a human to drive a car would maybe be $50k per year, so i'm not sure how a $200k vehicle can pay itself off in a few months vs a $50k car + $50k per year driver.
I'm aware that the cost / ride is higher for Waymo, but it doesn't sound like that would be enough to cover the extra $200k and not certain that scales to other geographies outside of SF.
I mean to pay off a $200k vehicle in a few months you would need each car to be clearing $3k a day in revenue or something like that.
It's probably a few years per car if they are at $200k. If they are 'in the black' or not will probably depend more about their accounting rules (i.e. depreciation) more than anything else.