You can be cash-flow positive driving Uber, but still lose money overall. Depreciation can be sneaky because you don't pay it until you switch vehicles, and even when it comes time to pay it, the costs are bundled up into the next vehicle loan you get. Maintenance is the same way.

Uber exploits the fact that people mistakenly believe cash flow is profit.

I also wonder if your father purchased commercial insurance. That stuff is expensive, and not having it is like buying an exploding lottery ticket. If he's ever in an accident (regardless of whether he was getting paid or not) and his insurance discovers that he drove for Uber without the appropriate coverage, the claim could be denied.

Uber also exploits the fact that their drivers can get away with not being adequately insured.