As a worker at a pawn shop I can confirm this theory
There are two things that give it away. One is that the cameras obviously can't wait around all day for people with interesting things to sell. They go out and find things to be on the show and come back and video them.
Two is that people with interesting things to sell do not sell them to pawn shops.
If you look around Youtube you can find a video of Rick working his shop before Pawn Stars and it does not look anything like it does on the History channel. It looks like a pawn shop.
The truth is that the History channel wanted to have actual ratings, and certainly noticed that Antiques Roadshow gets big ratings (on a channel that claims to not be about ratings but actually is). How can you have Antiques Roadshow but not obviously have it be Antiques Roadshow?
So they crow-barred
antique Historical items into it to justify it being on History, a channel that claims to be about History but actually is not. And then it worked, so now there are copycat shows such as Storage Wars and Pickers that are also Antiques Roadshow but, you know, not Antiques Roadshow. There are the items, the stories, the Lotto-mentality money happening, but no mandolins playing so you know it is not on PBS.
And they are all fake! People would not negotiate on camera. It's all fake. Ironically, Antiques Roadshow can claim to be unique and special and thus justify its existence on PBS because it's not *totally* fake, only
partly fake.