Most Truckers are paid by the mile... So if your sitting in traffic no pay (next time your stopped in traffic look around, how many semi's are sitting with you, most of those drivers are doing it for free)
Then there is load and unload time, which for some companies is non-paid, other is a nominal flat rate of like $35 that could take up hours of your day.
Then there is the "hours of service" which many companies require their drivers go "off duty" when they arrive at warehouse, but the warehouse required them to monitor the CB Radio to be called to pull into a dock, so their "sleep" time is taken up waiting to be unloaded, and they do this waiting for free.
Trucking companies need to end the practice of per mile pay, and start paying drivers Per Hour or a Salary (non-exempt) like every other company.