Guess it becomes illegal when your eye lids starts lowering ...

Fair, I checked and it turns out I must have misremembered the legality aspect. There are, however, safety recommendations that strongly urge to take a 30-45 minute break every 3-4 hours of continuous driving, and - IIRC, that was many years ago - the model S range was more than enough if you followed those recommendations and recharged during downtime.

Most, probably 40-something, states regulate it either explicitly or implicitly.

As we know from many other subjects, anything short of federal regulation is roughly equivalent to “unregulated” for the purpose of internet hand wringing.

Do you have an example of it being regulated at all?

Virginia, Colorado and Nebraska prohibit more than 13hr, 12hr and 12hr (in respective order) in a 24hr period.

I can keep going...

Thank you for sharing this. I wasn't aware any states had such a thing. I'm happy to be shown the evidence that some do.