But in all seriousness, although I understand that people like to out-cynic each other, over the road trucks seem to be pretty well-maintained. Whether that's the result of safety regulations and enforcement or simple economics (a broken-down truck is not a moneymaking truck) is left as an exercise to the reader, but either way you do not see a lot of barely-making-it or broken-down commercial OTR trucks on the road. That level of poor maintenance is generally the province of private vehicles.
That said, I agree there's plenty of incentives for the trucking companies to go the autopilot route.
Fatigue and sleep deprivation are chronic problems in the trucking industry. Clearly, many drivers are unable or unwilling to maintain themselves.
https://www.nytimes.com/2014/06/17/business/truckers-resist-...
http://www.huffingtonpost.com/entry/congress-made-trucking-d...