It enforces the 40 hours a week. That's the job you are paid for. Working 16 hours a day..7 days a week is not lazy. It's a recipe for burn out. Working hard for the 40 is what is expected and should be exactly that.
You pay me for 40 I'll give you 40
You want 80 then you pay me for 80
I don't think working 80 is either sustainable or even possible for that matter.
My wife was on an assignment in South Korea and she experienced the 16 hour work days there. No one even blinked when you tried calling your colleagues at 11:00pm.
However, what my wife noticed is that most of the people working those hours seemd drousy, unfocused and inattentive. It boggles my mind how either of the sides of that work contract can think that that kind of situation is beneficial for either of the sides in any imaginable way...
You pay me for 40 I'll give you 40 You want 80 then you pay me for 80