The reason why piracy can continue to exist is licensing agreements.

Content providers need to offer a flat rate for resellers, and sure, they'll have the occasional exclusive and better deal to specific online stores.

But compare this to a real world store: they can sell anything they can buy. Yes, they have to negotiate with a distributor but it isn't nearly as ridiculous as the digital marketplace is.

I should be able to set up my own ebook / movie / tv-show / game online store and be able to sell anything that isn't locked into an exclusive agreement.