Is it because every car looks the same when completed? Chip Foose has one look and applies it to every car that lands in his shop. A once proud classic muscle car is pimped out with 20" custom rims (that look like they've been dipped in chrome) The engine is ripped out and replaced with a SBC crate motor, custom paint, did I say custom paint? I think 90% of the focus is on the paint, and a stereo system so overkill that even low-riders would be in awe. It just seems that no matter who owns the car, the build is the exactly same. Imagine what they would do if they got their hands on your nice P-car.
Now.... Gas Monkey Garage gets it. They have a different style and usually retain many of the stock features. I actually dont think I've ever witnessed a stereo install on the entire season. Cool shop.