I think for Tesla, it is less about the workers and more about the entire design process at other companies that they're skeptical of. There are alot of items in the product design and manufactoring for GM, etc. that are there because "they've always been done", and it's difficult to tell from the outside what's important and what isn't.
Toyota's approach is different in that it takes in more input from people on the manufactoring line who are actually doing the work. It also helps that when they were getting up and running, their geography meant that pretty much everything they need is in a relatively short distance and they can make changes without needing to worry about long shipping times.
The "Big Three" which cares more about central control of the product and using their size to get everything done more cheaply. Their advantage is having the world's largest economy available to them so they have many suppliers to choose from.
Tesla's approach is that they're better at the technology and if you can throw more computers/robots at the problem eventually you can conquer anything. I think they're learning that this isn't always true, but it's still one of those cases where they're going to reach for the toolset they know best first.