For example in the UK the police did a sting simply by wearing expensive watches, and caught 31 robbers in a 12 month period.

https://www.bbc.com/news/av/uk-68003783

I agree that all the random factors you mentioned exist, and the proportion to random vs targeted theft would be an interesting debate, but there's solid evidence for significant targeted theft. The fencers tell the thieves what to look for.