It's not like you can fire employees on a whim: the “unrelated reasons” have to be substantial ones, and it's not clear you can find ones for any employee you want to fire. (Otherwise, you could use such a mechanism to de facto compel your employees to do pretty much anything you want.)
Also, even if you somehow did manage to de facto demand workers to work ten hours a day, if you have to pay hours beyond the eighth as overtime (with a hourly wage substantially higher than the regular one), then it's cheaper for you to hire ten people eight hours a day each than eight people ten hours a day.
(Otherwise, you could use such a mechanism to de facto compel your employees to do pretty much anything you want.)
Only if they can't get another job.
Here's the new thread for posting quotes, with the usual rules: