With regards to why not move sooner, isn't the company going through an entirely top-down overhaul starting with the CEO? If someone wants to be part of that change, and if they still believe in the ride-sharing space and if they were never in the crossfires of any of this anyways, then all of these are valid reasons to stick around.
If Uber had ethical leadership, there would be no worry about any of the technical talent, and they would be the very same people.
That worked adequately for industrial work. But for creative work, following isn't enough. Our whole field is about making computers do the dumb stuff so that humans can focus on the smart stuff. The SV startup model gets much of its economic power from the way that a small group of people can out-think, out-innovate large companies that operate along industrial lines.
But that only keeps working as long as individuals have a fair bit of autonomy. Which in turn only works as long as workers are able to think for themselves. As David Marquet wrote, modern effective organizations don't move information to authority; they move authority to information.
I want to build teams that can spot a ball, pick it up, and run with it. That doesn't work well if they have to run every detail up to the CEO for signoff.