I view the original competitive edge to be the "Warehouse as a Service". Anyone can sell their products without having to own an online store or get the bulk sh

I view the original competitive edge to be the "Warehouse as a Service". Anyone can sell their products without having to own an online store or get the bulk shipping logistics figured out, just ship it in to Amazon, and they can load balance your product out across the US to make that 2 day delivery possible. They also did have the original patent on "1 Click Purchase" which I'm sure has always helped sales. EDIT: So the only reason I think it hasn't been copied is the high barrier to entry and market inertia as the other commenter said.