This I agree with. I was very familiar with the business domain and the technology they had been using. So yes I agree if either of those were radically different it would be much harder. Good point.

Tesla uses lots of GPUs for training autopilot, I would be surprised if they wouldn’t have people writing optimized shaders for some of the tasks.

You're missing their point. They're using that as an example of how domain knowledge can be important. It's a really naive take to think all/most of the code written for a social media platform will be immediately accessible to people writing code for a machine learning+robotics platform or for people writing code for an entertainment console. In fact, it's entirely possible to have created these things without any overlap in technology.

Those people will have all the time they need to talk to as many engineers they need to understand the code base. Maybe a person hasn’t worked with shaders before, but then it’s a great time for the engineer who writes the shaders to teach him about how the GPU works with some code examples.

This operation is not just interviewing people, it’s a kind of knowledge transfer and finding the people who are the best at explaining how the code works and can answer deep technical questions. This is how Elon works generally (if you look at the SpaceX interview, you can see that he just goes to people and asks them questions about the parts of the rocket while he’s doing the interview).

Yea. I think that’s the opposite point that you’re trying to make. That’s what would make them less qualified as reviewers since the domain is very different.