Earlier quoted context omitted.
I wouldn't be surprised if they start out with "last mile" drivers to deal with off-highway driving.
But the last mile is where driverless trucks are most useful. For long haul, you can just use trains.
Example: you have refrigerated items (let's say a shipment of fresh fruit) that has to be maintained at a constant temperature and you want it delivered to your customer on Thursday when you ship Sunday night.
Truck: not a problem, and you can easily get updates all the time from dispatch (or if there is a GPS unit on the truck, immediately).
Railroad: maybe they will get it there, maybe they won't.
If the railroad puts a refrigerator unit on your boxcar and it breaks down, too bad - they won't reimburse you. A trucking company will.