The two camera stores for which I worked (in different states) back in the 70's and 80's always took down info on two forms of ID, including a driver's license or other state issued ID on any used equipment we took in. That way we could always track back responsibility for stolen goods. I'm not sure if it was law at the time, but any reputable dealer seemed to do this. I was surprized at the number of people who suddenly "decided to keep" their cameras after learning this. We tried to get car license plates on people who did this in a very suspicious manner. and shared that info with other local dealers and repair shops.
When I worked in Minneapolis, I heard that cameras were often stolen "to order" for people in Chicago who placed "orders" with a thief who would go to other cities in the region and steal cameras. I knew one person in Minneapolis who had her Leica CL stolen and it turned up in the hands of someone she knew in Chicago in a very short time.
BTW, KEH is sending people all over the country purchasing used camera equipment in bulk from camera stores. I found this out at the local "pro" shop
when I asked about used equipment. KEH bought everything used they had for about $5000 a couple of weeks before I was there. That included three Nikon F5's.