I don't see Alibaba or eBay as competitors to Amazon--the former because it doesn't really operate in the US (almost nobody in the US would know what Alibaba is

I don't see Alibaba or eBay as competitors to Amazon--the former because it doesn't really operate in the US (almost nobody in the US would know what Alibaba is) and the latter because it just serves a completely different market with different mechanisms and so on. Shopify might be, but it's so tiny in comparison it's hardly unreasonable to suggest it isn't a legitimate competitor. Wal-Mart, on the other hand, might be nearing that status as far as eCommerce is concerned.