Logging software uses GPS. If they jam it they can go off route or otherwise not have big brother watching them. I imagine it's becoming somewhat less prevalent though, as it's widely known they do it, enforcement has ratcheted up, and it's obvious when trucks just drop off the face of the earth all the time. It's not like 15 years ago when cell networks were much more sparse.

At a guess, I'd say the way they drive is tightly controlled by hiring companies via GPS logs (eg too many / not enough breaks, no driving over / under speed).

Driver fatigue rules often require mandatory rest stops. I. The past this was achieved by writing the rest break in a log book and taking some more uppers. Pesky GPS trackers showed that the break wasn't being done.

It's also traditional to take a load to a yard and rip out the good stuff and reseal it. Chain of custody in shipping is pretty weak. So much more painful if being GPS tracked.

Delivery drivers get rewarded for making all their runs on time, and getting streaks of on time runs, but this is often impossible. So they hand off some deliveries to third parties. But that is very painful if your vehicle is being tracked. GPS is often wonky in urban areas so hard to know for sure if a driver is fuzzing some runs.

As fleet management software gets smarter it will become pointless. But there is a disincentive to fixing log forgery -- cheaper freight. Deaths are externalized costs.