The average truck driver earns about $70k a year. Even assuming that the sensor suite costs as much as an entire Tesla Model S(which in addition to a sensor suite includes an actual car), the system will pay itself back in a year.

Also once automated, the trucks can engage in all sorts of hyper-miling shenanigans since they don't have to worry much about traffic during a significant part of their 24/7 operation, especially on more remote roads. That's additional fuel savings.