A big test for the self-driving truck industry is beginning this week, courtesy of the U.S. Postal Service. The USPS will be transporting mail between Phoenix and Dallas via self-driving trucks from the San Diego-based company TuSimple. Each of the 5 round trips will span 2,100 miles and 45 hours of driving. A driver and an engineer will ride along in the vehicle for safety purposes. The USPS says the program is aimed at improving safety and service, reducing emissions, and saving money. How far away are we from self-driving vehicles being commonplace? Do you trust them or does the technology need to improve?