Here's a slightly earlier article about this: http://www.phillymag.com/news/2016/03/25/speeding-ticket-sca...

Nothing in either story explains why the victims would be geographically clustered in Pennsylvania. But if the scam was prevalent elsewhere, I'd think we'd be hearing more people saying "I got one too!".

I wonder if there's some other angle than a shared smartphone app explains the locality better: a disgruntled neighbor with a radar gun, or something. The obvious problem with any local theory, though, is that it would have to explain discovery of the email addresses.