In a grandoiese way, I believe those "employers" who do NOT offer per diem, do not have the worker's welfare in mind. There are those, who care and in addition, will offer other extras such as a medical and/or dental plan. Maybe even a 401K or profit sharing of some sort. In the end, those who do offer the few extras, abeit with a small cost, can do much better business. Why? Because if the workers have the choice of working for two different firms to get a job somewhere, assuming the basic payrate is reasonably close, they'll choose the one with the "extras". This is an example of what makes the subject of "economics" so much more complex and less of a science, than an art. Studying how these things work. HOWL!!!!