But a lot of your argument here is presuming that yards are relatively clear or that it's as simple as sticking cameras and sensors to a truck.

No, my argument is that a complicated/hazardous yard won't prevent autonomous vehicles from proliferating quickly and putting over-the-road drivers out more quickly than they may think.

Like I said, trucks may need human handlers within the confines of the yard, but there don't have to be many and they don't have to be expensive.

But the ethical question is should you let a computer drive a car without someone behind the wheel in case something goes wrong? What happens if the program stops, or has a blue screen as it were while the car is driving 65mph in rush hour?

It's the same ethical argument against human drivers: should you let a human drive a car without a backup human in case something goes wrong? What happens if the driver falls asleep or has a heart attack while the car is in motion in rush hour?

Statistical accident rates will win out - one-off cases will not be relevant, ethically or otherwise. Except for the actual victim, reducing automobile overall (assuming that's possible) wins over the occasional computer malfunction.

Once the two options are in coexistence, we'll have some real-world numbers to crunch and see which is safer overall. Decisions will then be made very rapidly.

But people can make mistakes, and even a network or cars and semis working together can overlook obstacles.

Right, and especially when they're relying on reflexes and biology at high speeds.

Humans will always make mistakes, but you can improve an algorithm. It's hard to improve biology (yet).