I actually had this happen once. I charged my return flight, and sent them a bill along with some legal letterhead, for the flight, an extra day hotel stay, and 3 taxi trips. My lawyer made 2 follow up calls and it was paid within the month. The outfit in NYC, is no longer in business. I wonder why. I still remember his sob story about needing the money. Hard to need the money more than someone trapped 1000 miles from home. Dispite being non-religious, I sincerely hope the lowest depths of hell await these types of people.
One time my company flew out an interviewee, he was great but decided to go with another company -- that he interviewed at during his trip. Although me and my co-owners were a bit miffed, the idea of cancelling the flight is beyond the pale.