griffincat,
From my understanding--that is one of the trade offs with the discounted postage. They don't "have" to scan packages with the discounted postage individually, but they do have to scan the form if you have it.
Lol, and if they know what it is. Most of the clerks at my PO don't know what a scan sheet is. I tried it once, and was told the scan form wasn't USPS and I was confused. BUT I do have a good PO, I just have to drop at the counter or in the box they have for packages and they will scan them all individually before it goes to the sort facility (98% of the time)--just not then and there if they are busy. I only go to the counter for the stuff I have to--express and sometimes international.
I would say if you don't like your PO, check out another one in your area if that is feasible. The knowledge/service from PO to PO can vary considerably.
Oh and hi Julia, glad you were able to find what you were looking for :o)