Tesla is so secretive that nobody outside really has a clue what the problems are. Even the automotive trade press doesn't know. There are so many possibilities. As I wrote last time this came up, Tesla would probably be better off letting some competent automotive reporters tour the plant. Right now, investors are assuming the worst.
What's surprising is that Tesla is also having trouble with battery pack manufacturing. That's far simpler than building a car. It's a good job for robots, building identical units made of a large number of the same components.
I don't think Musk is running different companies at all. They are all the same, working towards the same goal - a city on Mars. Such a thing, should really benefit from totally automated factories.
Tesla isn’t pushing the standards, they’re not even playing in the same league as Toyota and other established manufacturers. But they sure are good at hyping their flawed methodology.