I seriously doubt anyone at Nelson's took the fliers out. Having helped stuff the newspapers years ago I can tell you what is more likely is that each store only provides certain numbers of fliers. In many cases that number doesn't cover all of the papers we stuff, mail and sell. When that happens, we use as many of the fliers as we can and once we run out we keep getting papers ready without that flier.
With it being a holiday week, our sales numbers will have increased so there were more papers than normal. If Great Lakes (or any other store) didn't provide more fliers, eventually we'll run out of papers with all the fliers and be forced to start selling the ones that are missing some items. There have been times that we've had 5+ fliers and the last of the papers will only have 1 or 2.
We also occasionally run into extra problems on holiday weekends because the stores typically want to keep additional fliers at the store so they have enough for the extra customers. That means if they didn't print more we wind up with even fewer fliers.
And as far as the product they paid for... If I remember the billing correctly (and Kathy may be able to correct me) they are billed on a per thousand rate and it is based on the number of papers we mail and sell with their flier (or how many fliers they provided, can't really remember). Either way, I don't believe they get charged for papers that don't have their flier.