The two decades during which human oversight of automated systems will be mandatory would be long enough for me to finish off my career getting paid to drive while I sit in a cab writing code, periodically checking over the status of my lead truck and the two or three slaved trucks following me.
Trucks and cars are different. They've been running automated big rigs between Dallas, Houston, San Antonio, and El Paso for a few years now.
Given the significant weight and danger of death for other drivers, it'll be years until legislators allow their "safety drivers" to be eliminated from the equation. This makes the AI system more akin to enhanced cruise control than robotic trucking.
Here's one article about Volvo:
"Companies such as IKEA, UPS and FedEx have begun using autonomous trucks to make long haul trips across Texas, most often along I-45 between Dallas and Houston. In 2017, the U.S. Department of Transportation designated Texas as one of that nation's 10 proving grounds for autonomous vehicle testing. And Texas lawmakers have encouraged autonomous-vehicle development by making sure traffic laws do not encumber the companies." https://www.houstonchronicle.com/business/retail/article/vol...
We’re far from self driving vehicles still, and trucks will be the last to be automated, and once they are, I expect they’ll require human supervision just like you predict.