Manufacturing an electric car isn't that much different from making a gas-powered one. Sure, the propulsion systems aren't the same, and it takes much longer to "refuel" an electric car by recharging than it does to pump 15 gallons of gas into a traditional automobile.
But the basic engineering of an EV is well understood and has been around for a century: batteries, motors. Tesla has added a lot of software, overcoming some of the electric car's limitations. For another carmaker to duplicated Tesla's efforts, however, is trivially simple. General Motors brought a long-range EV — the Chevy Bolt — to market in about a year and half.
Theranos claimed it was commercializing cutting-edge research that would revolutionize the accepted science of medical testing. That science was intricate, and as it turned out, challenging for actual scientists and physicians to figure out. But that confusion could generate a smokescreen, a fog of hard-to-comprehend concepts.
To be sure, Musk at times tosses out engineering concepts that could confuse the untutored. But the auto industry has been doing the same thing for so long that it's easy to determine if he has a point or is simply engaged in distraction.