...What would they do with it? The business model (also uber) as-is makes a loss.
Uber/Lyft's initial proposition was that once ride sharing incumbents were established, they'd have a software-ish monopoly and margins. This did not work out. Now the proposition is "When driverless cars get invented..."
If google had a car that can drive itself, they can figure out an app. They can get to a customer base. The driverless car is the important part.
Amazon otoh... deliveries maybe? If they could figure out a way to do deliveries in a lyft/uber model... that's valuable to amazon.