Unfortunately, that driver is about to find out what "two party consent" for recordings means.
Also, for all we know there could be a sign in the black car that says, "Smile you're on candid camera!".
I don't know whether California is a two-party consent state, and the specifics of what that requires are different state to state anyway.
If it was your car and someone got in and recorded you, then I'd say that's more clear cut. But if you get into someone else's car do you have a reasonable expectation of privacy?
As a passenger, I think I'd be happy to have an example made of a driver who recorded and then published video and audio of a private conversation without consent. I've said and done plenty of things in the back of an Uber/Lyft/taxi that I wouldn't want the whole world to see.
Having issues with Uber's practices is fine, and talking about them publicly is fine—but a driver who makes and leaks illegal recordings is not someone I want to ride with. Throw the book at him, IMO, and frame it as standing up for riders' privacy.
EDIT: Er, scratch that. Didn't realize there was audio attached. I think audio might be the incriminating factor in the two party consent thing. I mostly just wanted to make a bad pun.
However, CA does make an exception for recording "in any other circumstance in which the parties to the communication may reasonably expect that the communication may be overheard or recorded."
You could certainly make an argument that this douchebag might reasonably expect audio to be recorded in his company's driver's cars. Not so sure you could make that argument for the other passengers.
Interestingly, Bloomberg could be sued (or prosecuted; $5000 fine) for distributing the recording if it indeed falls under CA's wiretapping laws.