If you ship me drugs I know you are a Tor user in your city. How many regular Tor users does your city have? People in higher population density areas, and more urbanized areas, may not have to worry as much about this sort of attack. But if you live in a rural area and ship drugs from near by, the fact that you are the only Tor user within a 100 mile radius of where these drug packages are being sent from is not going to turn out very well for you even though there is a Tor user 2000 miles away from you using Tor to look at legal porno.