Waymo has made a lot of progress with self-driving cabs. It completes more than 150,000 driverless rides a week. Tesla hosted a Robotaxi Day to update investors on its plans and t

GM just walked away from its robotaxi dream, bailing on its Cruise business as the price tag became too much to stomach. Between the lines: GM can't afford — the cost or the distraction — to work on a moonshot when its core business needs fixing.

For others still developing or operating robotaxis, GM's Cruise exit sends a clear warning, said Philip Koopman, a Carnegie Mellon University professor working on autonomous vehicle safety.

Microsoft will take an $800 million charge on its investment in the Cruise robotaxi business after General Motors announced it would no longer fund the initiative as part of a shift in its autonomous driving strategy.