There are many jobs like this. I have a friend that has a MBA and was a banker for Bank of NY. Her area was the Pacific North West. If she got stuck in Boise because of weather for a few days she didn't get extra layover pay. All she got was per diem for food and shelter. Many times she'd miss weekend events because of this.

Another friend of mine is a Analyst for Raytheon. Same thing expect he gets stuck in Greenville, TX for days at a time.

Unless things have changed considerable in recent years that is the way many are compensated. I receive things in my email about sales positions every now and then. Most of them seem to pay based upon straight commission or draw against commission. Most are with major corporations. At one time I had 91 salesmen working for me. Most of them earned a pretty decent living working on commission. If they were not making money then they were not working. They could start earning money from the first day. There are some companies where a salesman may be paid a salary due to the length of time that it takes to close a sale. For instance, a heavy equipment salesman may be paid a base salary due to the length of time it takes to close a sale. He may be paid an additional commission or bonus with each sale or on his sales for the year providing he exceeded his quota. I believe IBM used to pay their main frame salesmen a base salary due to the length of time it would take to close a sale. As far as the $250/week draw is concerned, that was as an example. I considered going to work for a major stock brokerage firm at one time. They paid sales people a draw for a certain period of time and then you were paid straight commission thereafter. That has been some time ago, but as far as I know that is still the way those people are compensated.