A friend who is an airline pilot once told me one of the stewardesses made hamburgers on the hotel room iron, to safe money. They actually get an allowance to eat at the location, still she did that. So stingy.
They get paid a set amount every day for food, regardless of what they get. If you are getting a flat rate $50 per diem for food, it makes financial sense to eat cheap and pocket thr difference.
An allowance sounds more like something added to their paycheck, rather than something they expensed. If that was the case, and they got to take home the allowance... well, heck. Ten bucks is ten bucks.