not that it necessarily changes your argument, but the signup bonuses that uber / lyft offer are significantly higher than $5 (closer to $1k), and are structured in such a way to ensure you're not dual-apping.

"A different model of what they are doing is using their massive revenue growth (not profit) to raise money to fund a search for real pricing power with food delivery, shared bikes, and Uber freight."

I suspect this isn't far from the truth.