I’m not sure this is actually true over the long term. Ultimately, it’s supply that matters because of the direction of the transaction.
For example, let’s say Uber couldn’t lock in their best drivers and it was in their best interests to leave Uber because they could make more money (e.g. keep the commission on transactions). Then, by definition they would successfully compete for transactions with Uber. (If not, they’d be locked in). And since Uber makes money on commission, and the drivers own the full stack, they can compete away all of Uber’s margin.
One by one, the best drivers would leave and only the struggling one would remain – the ones that have no choice. At that point, Uber would be able to stronghold demand.
This doesn’t happen because drivers cannot compete- they are locked in. And this is deeply linked to the nature of supply and demand – much more than a single company’s ability to execute.