They also have to work in the rain, and in the snow, and work extra hours before Christmas, and lift heavy boxes, and all sorts of other stuff goes with the turf when you're a trucker.
That I've heard, with the insane pace of work that Amazon tries to force 'em to maintain, 3,600,000 milliseconds per hour, the job would be very little better if they somehow had 5-star resort bathrooms folded into hyperspace inside their trucks.
Similar to farmers working in the fields - they didn't walk all the way back to the farmhouse if they had to pee.