I think this job is just so different than working for a company though. We prepay for that child's food, art supplies and what ever else we incur each week. Not to mention income coming from a company versus a person just has different levels of security (in regards to knowing you will receive it).
That said, if you have a deposit to apply to that week (or 2) of care if the family runs off you still get paid for the days you worked...you would just be out the weeks of notice they are supposed to give.