I'm not super convinced most people will do more work on-site either, I'm just pointing out the immoral position you put yourself in by working two full-time jobs at once.
I think a lot of companies have poor project management & employee performance measurements, so half the time, people only have half the picture or don't know what the heck people are supposed to be doing and if that's actually getting done. That only becomes more complicated when projects are abandoned and/or requirements shift every quarter.