Approval: Requires invoice for a 300-unit sale?

I have just opened up an Amazon seller account and I am very confused and frustrated. I thought the idea behind being an Amazon Seller vs an Amazon Business is that you get to sell products that are already on Amazon and being sold by others. However, every single product I try requires approval. But that’s not even the issue. When I try to request approval, it says that I have to submit an invoice from a manufacturer or distributor showing that I’ve sold 300 units of a product. Does that mean Im supposed to be storing my own inventory? Or that Im supposed to buy 300 units of a product from Amazon and store it at their facility? And wouldn’t that make me an Amazon Business rather than a seller? That just seems like kind of a scam to me.

Trust me when I say that I’ve searched for hundreds of products and they ALLL require this type of approval. I even have lists from others of hundreds of products they claim are undated but they’re not. Even audible and kindle books require approval.

I have a legitimate business idea that Im trying to implement using Amazons seller forum. If I had to buy inventory then I’d just forgo Amazon and start the online business the way I’d really like. It feels like a shady thing to insinuate people can do this when really they’re just tricking people into buying inventory that they have to sell on Amazon. That just forces people to buy inventory they don’t necessaily want just so they can get started but really it’s so Amazon can have more products to sell.

What am I missing? Im really hoping that my understanding of this invoice issue is incorrect. Can someone help me understand better and provide more information on how to get started?

Thanks for your help.