Debate rages over whether semi-autonomous cars are a good idea—even at Elon Musk’s automaker. Shortly after the Tesla CEO boasted last year that his cars would soon come with the capabilty to drive themselves, the head of the company's Autopilot technology, Sterling Anderson, resigned.

The Wall Street Journal reports (paywall) that Anderson's replacement spent less than six months at the post before he quit, too. It's part of a pattern of high turnover that has plagued the Autopilot team, fueled by a concern over "reckless decision-making that has potentially put customer lives at risk," as one engineer who resigned put it. 

Mobileye, the company that supplied the brains behind Autopilot, also parted ways with Tesla last summer, after a high-profile crash killed a driver while the self-driving system was engaged.

Tesla's approach to self-driving technology is different from the one most other companies use. In most cases, lidar sensors are the centerpiece of an autonomous car's sensor package. Lidar is great for building a highly detailed 360-degree view of the environment, and it can work at long distances. Autopilot, on the other hand, relies mostly on building a picture of the world from a combination of radar, ultrasonic sensors, and cameras. This is easier to build into a car and less expensive than a lidar-based system (though that might be about to change).

But critics say Tesla's setup isn't ready for the kind of autonomy that Musk talks about. And now, evidently, we know that the company's own engineers feel much the same way.