Lyft is more expensive, which explains its better pay and its smaller ridership. I don't think this is sustainable because of what you've observed, which is that the smaller ridership pushes drivers away from the platform, making Lyft less appealing to even the people willing to pay (longer wait times, smaller chance of getting a carpool, etc).

I think it depends on the market. Lyft here (Philadelphia) is the same price as Uber just about, and they both run promotions all the time. Car availability is the same in my experience and most drivers seem to do both. Drivers seem to indicate that they get better subsidies to drive from Lyft.

I'll admit that lately I've been mostly taking Uber because it's cheaper than Lyft. So that probably explains it - Lyft simply doesn't cut prices as aggressively. (But I still check both because sometimes Lyft is cheaper).