They're not blocking the signal from their own cars, but from their employer's. And possibly using it to cheat on their taxes as well.
They could probably put a stop to this by making jammer detectors and inspecting for them at weigh stations and then checking the logs on the GPS for anomalies. If the cops have a jammer detector, they can start pulling people over for having them.
If a few people lose their CDL, they should fall out of favor. These aren't very easy to hide, given that they have to broadcast to work. And if this pushes them to invent some other way to tamper with their GPS monitors, so much the better: it wouldn't cause nearly as much harm as these.
They could probably put a stop to this by making jammer detectors and inspecting for them at weigh stations and then checking the logs on the GPS for anomalies. If the cops have a jammer detector, they can start pulling people over for having them.
If a few people lose their CDL, they should fall out of favor. These aren't very easy to hide, given that they have to broadcast to work. And if this pushes them to invent some other way to tamper with their GPS monitors, so much the better: it wouldn't cause nearly as much harm as these.