Tesla co-founder and CEO Elon Musk believes that cars you can control will eventually be outlawed in favor of ones that are controlled by robots. The simple explanation: Musk believes computers will do a much better job than us to the point where, statistically, humans would be a liability on roadways.

"I don't think we have to worry about autonomous cars, because that's sort of like a narrow form of AI," Musk told NVidia co-founder and CEO Jen-Hsun Huang at the technology company's annual developers conference today. "It would be like an elevator. They used to have elevator operators, and then we developed some simple circuitry to have elevators just automatically come to the floor that you're at ... the car is going to be just like that." So what happens when we get there? Musk said that the obvious move is to outlaw driving cars. "It's too dangerous," Musk said. "You can't have a person driving a two-ton death machine."

Even if that were to be the case, Musk cautioned what would be a slow sea change in the automotive industry, something that's already been the case with hybrid and electric vehicles.

Self-driving cars would take 20 years to replace regular cars

"I think it is important to appreciate the size of the automotive industrial base," Musk said. "There's 2 billion of them." Moving everything to autonomous vehicles would take 20 years, he added, noting that the sheer capacity of car and truck production is limited to about 100 million new vehicles a year.

Tesla has already added some self-driving features to its cars, but is working on technology that will let the car drive itself completely. An "autopilot" mode introduced for the Model S will do things like change speed, brake, and keep you in the correct lanes using on-board sensors. The next logical step is combining that with highway driving and navigation features to let the car drive the driver. In an interview last October, Musk said models the company was working on for this year would be "90 percent capable of autopilot."

Verge Video: Elon Musk's self-driving Tesla Model S

Today, Musk noted that the hardest part of helping cars drive themselves is what happens when vehicles are traveling between 15 and 50 miles per hour. "That's where you get a lot of unexpected things," Musk said. That list includes road closures, open manhole covers, children playing, and bicyclists. Lots of things that your robot car could run into without human remorse.

15 to 50 miles per hour is hard

Aiding in that are automated systems that scan what's around them. NVIDIA's solution, called Drive, can identify people, road signs, and other objects, with the promise of learning behavior over time. That goes hand in hand with a digital dashboard and Nvidia's Drive PX, a computer with two Tegra X1s that can process imagery from up to a dozen cameras in real time. Nvidia's building that system for automakers with the hopes of powering self-driving cars of the future. Today Nvidia said it would be releasing a kit for developers in May for $10,000.

Tesla doesn't want its car fleet hacked

Besides improving onboard sensors and computers, Musk noted that there are some basic security concerns to square away before we can sit back and be driven around by cars. Tesla is trying to make sure that people won't be able to hack into its vehicles, be it a single vehicle or multiple cars. "We've put a lot of effort into that, and we've had third parties try to hack it," Musk said.

One thing that can remedy the security issue are frequent software updates, which Musk says will be arriving on Tesla's cars later this year. Details about that are coming in a separate press conference on Thursday, though Musk teased that the company would "end range anxiety," in a tweet earlier this week. It's unclear whether that means it will do a better job indicating a cars current usage and approximate range, or if Tesla's rejiggered its driving software to goose more miles out of a charge.

Update March 17th, 3:01PM: With additional quotations from the interview and link to the full keynote.

Update March 18th, 1:33PM: Following the on-stage interview, Musk elaborated on Twitter, saying that Tesla was "strongly in favor of people being allowed to drive their cars," and that he personally did not want drivable cars to be outlawed:

To be clear, Tesla is strongly in favor of people being allowed to drive their cars and always will be. Hopefully, that is obvious. — Elon Musk (@elonmusk) March 17, 2015

However, when self-driving cars become safer than human-driven cars, the public may outlaw the latter. Hopefully not. — Elon Musk (@elonmusk) March 17, 2015

Verge Video: Will cars ever drive themselves?