Well, often employers want to be able to reach employees at all hours of the day or night, especially those employees with specialized skills critical to production or operation. It’s a trade off. If you want to be able to call me at 3AM or at my son’s birthday party to get your power plant or oil refinery back up and running, then I’ll do whatever I like with your phone. Don’t like it? Then phone is powered down at 4PM and you can talk to me in the morning after you’ve lost 10 hours of production at $100k an hour.