California troopers pull in a Tesla Semi for inspection

Tesla CEO Elon Musk recently took to Twitter to admit that developing self-driving vehicle technology isn’t as easy as he’d imagined.

Musk is one of the most high-profile proponents of automated driving technology, but after having worked on the development of self-driving cars and trucks for years, he says that he finally understands that it is more difficult than he thought it would be.

In response to a Twitter user ribbing him over the missed target date for the delivery of Full Self-Driving (FSD) software for a Tesla Model 3, Musk responded:

Haha, FSD 9 beta is shipping soon, I swear! Generalized self-driving is a hard problem, as it requires solving a large part of real-world AI. Didn’t expect it to be so hard, but the difficulty is obvious in retrospect. Nothing has more degrees of freedom than reality.

Musk unveiled the electric Tesla Semi equipped with Advanced Autopilot crash mitigation technology in late 2017. While a handful of Tesla trucks have been spotted on the roads since then, the company is likely to again delay delivery of the Tesla Semi until 2022 as issues with battery cell supply continue. The company also lost President of Tesla Heavy Trucking Jerome Guillen in June when he stepped down after serving only three months in the position.

Other companies like Waymo, Plus.ai, TuSimple, and Starsky Robotics have been hard at work on self-driving truck technology for many years now, but many remain skeptical about how realistic it really is to take drivers totally out of the cab.

Raj Venkatesan, a professor at the University of Virginia Darden School of Business told the BBC, “It’s not clear at all now whether there will even be displacement. You need the back-up driver. Within the next five or 10 years, it seems reasonable to expect some movement towards autonomy, but with a co-pilot. In my view, it’s like a long-haul flight. The plane can be put on autopilot, but you still have the pilot.”