It's not. We're talking about people's lives.
I've felt tired before and you know what I do? I nap in the parking lot. Because the remote chance I kill or maim myself or someone else is not worth the momentary discomfort. It's not fun, and sometimes people harass you, but it's far better than driving drowsy.
> reasons to be tired and drive: rotating shiftwork, working multiple jobs, caring for a newborn, caring for the sick.
None of that is an excuse to get behind a many thousand pound piece of equipment and not be able to control it.
> "You should never get behind the wheel if there's a chance you'll fall asleep!" is an absurd thing to say.
I stand behind my assertion and hope you'll come around.