And i think it's OK. There is a reason why professional truck drivers must not drive longer than specified amount of time without taking breaks. Work safety regulations are usually written in blood.
But the work is fundamentally different. You can work 80 hours in retail for example. With Uber drivers it's not "drive down long stretch of road without a break for 8 hours".
Uber drivers are, well, drivers. I wouldn't trust somebody working 80-hour schedule (with everything that implies about their quality of rest, or lack thereof) to be regularly driving a car in public. That's just accidents waiting to happen.
No one should be doing 80 hours a week, that's 12 hours each day without weekends + commute (1 hour) + 8 hours sleep, 2 hours for eating and you have 1 hour left for the "all the other things". And thats if you don't have children. If you do you already spending more than 24 hours a day.