You all miss the point of course. You have these people that don't touch the cars, but pretend they do. TH is so polished it's stupid. But if you like the fake stuff have at it.
Straight Pipes do it themselves. Other than the race track videos, SG and Jack do it solo and the Car Wizard does his channel solo with his wife.
I don't see your point. One the one hand, you're talking about wrenching and / or not wrenching, like you're suggesting Sarah n Tuned does, or does not.
On the other hand, you're talking about video production, which has NOTHING to do with the cars themselves. The subject could be computers, or makeup tutorials, or airplanes, or whatever. What does the video production and the staff on hand (camera guy, sound guy, editor, etc.) have to do with the actual subject matter itself? pretty sure it's Thomas and James driving the cars, and at no point do they pretend that they work on the cars - not that that's the point of the channel.