There are two basic “selling plans” - Individual, and Professional. More information can be found in the [Participation Agreement (link, Customer Help Content)|https://www.amazon.com/gp/help/customer/display.html?nodeId=1161302] you signed.
> And where would I get an invoice from a distributor when the item was purchased at Walmart or the local Dollar Store? Do they want a receipt? I don’t get it.
That’s the point you’ve run afoul of - this practice of purchasing in non-wholesale lots from retailers is what’s known as ‘Retail Arbitrage’, which has always had restrictions on Amazon, and is now becoming even more restricted due to the headaches RA imposes on Amazon when used by ‘casual’ sellers.
Amazon no longer wants goods purchased via retail channels on their sites, they want people & companies who are in and of themselves retailers - and whether that entity has signed up for a Professional or Individual Selling Plan, they want all to operate professionally, and abide by professional standards. As others have mentioned, there are venues better suited for what you’re trying to move. As a well-respected forum regular recently opined, “If The River gets too rocky, you can opt for the calmer bay.”