If you can get your work done accurately in four hours, you should still get paid eight. Unfortunately, they want you to do more in the remaining four, even if your moron co-workers requires eight and are paid the same or more than you.

There are also no guarantees you will be rewarded for the difference in productivity.
And, it’s also easier to dump “other duties as assigned” when you are physically present.

Employers only want to use technology to get more work out of you after you’ve put in a full day in the office, not to make your full day better. That’s a shame, as the two biggest impediments I’ve discovered to getting work done in an office are physical aspects of the office and your co-workers.