All retail includes B+M stores no? Not necessarily a fair comparison. Same article says they control 49% of US E-commerce.
https://techcrunch.com/2018/07/13/amazons-share-of-the-us-e-...
https://techcrunch.com/2018/07/13/amazons-share-of-the-us-e-...
What I care about is obtaining a product. Segment by non-substitutible category (book vs electronics, etc) but not delivery method.