that is true, especially when you hire your drivers from "poor" countries (to pay them less...) and you have to be sure they make their job and don't steal your load or even truck...
Not only that, if you pay some amount of money per hours and your transporter is taking too long, it's easy to check if there are any problems or he's taking another route for his own things
Is the transporter route going to be recorded? That could be useful in case of delay in delivery.