If you read it, the scanner software they wrote is pretty specific to this exact skimmer. It looks for the default id of those Bluetooth modules and then sends a couple commands to see if it gets a particular response.
In other words, the scanner isn't really general purpose enough to have in every pump and it's easily defeated by very minor firmware tweaks or even just changing the Bluetooth id of the device. You'd have to have something much more complex to be reliable, and it'd have to have some sort of facility for updating it's signature database akin to a virus scanner. Gas station owners don't have much incentive to give a damn currently, especially not if it involves retrofitting a fairly complex device onto all of their pumps that they also have to pay for a service that provides updated device signatures.
In other words, the scanner isn't really general purpose enough to have in every pump and it's easily defeated by very minor firmware tweaks or even just changing the Bluetooth id of the device. You'd have to have something much more complex to be reliable, and it'd have to have some sort of facility for updating it's signature database akin to a virus scanner. Gas station owners don't have much incentive to give a damn currently, especially not if it involves retrofitting a fairly complex device onto all of their pumps that they also have to pay for a service that provides updated device signatures.