If you can create a long haul tractor trailer, that can drive with little/no human intervention, major shipping companies would likely shovel cash in your direction. A quick Google search suggests that the average semi is driven about 45,000 miles per year. If the driver is earning $0.40 per mile, that's a savings of $18,000 per year per truck. FedEx has 20,000 semi trucks in its fleet, Walmart has 6,000. As an aside, I read that the US had a shortage of 50,000 drivers in 2017.
The market might be smaller than passenger vehicles, but the impacts on labor costs are significant. The savings to your average home/consumer are the loss of time while driving, this really doesn't hit your wallet. It's not like you are loosing money by driving the car yourself. For shipping companies the driver is an added expense that needs managers to schedule drivers, and people in HR to manage benefits.