Honestly it kind of sucks but I can't really imagine why it'd be illegal, and it actually makes good sense for the business particularly when you work on commission. I mean, theoretically, you could go to a bunch of friends, "sell" each of them a couple hundred dollars worth of stuff (Or one GIANT purchase to one friend, to be less obvious), tell them to cancel the cheques immediately and get your commission for a massive scam. I worked door to door doing labour a few summers ago and that was commission where we were paid in cash at the end of each day, before cheques and credit cards could possibly have been processed. I'm sure there were a number of guys there doing that (If they weren't just doing the sales off the record and pocketing 100%, which many of them were.)
Come to think of it I get why that company ripped off their customers so much, 90% of their employs were ripping THEM off, so there was a lot of overhead.