Sorry, I've just understood your point. Duh!
True, if people don't order, they won't get paid for today. However, when I said that they won't be able to afford to decline the work, I meant that they may be scared of saying no and missing out on work in the future, rather than needing today's pay. Of course, the latter may also be true.
I used to work with a group of very disadvantaged young people, many of whom were delivery drivers for a well known company. They felt obliged to take the work that was given to them because they were worried about saying no. They probably could have managed without working for a day but they were always scared of missing out on further work as a result of calling in sick etc.