[supercon]

I think that the term 'salespeople' here refer to those who proactively push their products to the market and by doing so widen the market for the company they represent.

The examples you give are indeed places where buying or selling happens, but where does the incentive to do these transactions come from? It's still from humans. Sure, we are bombarded left and right with ads that were carefully targeted for us by complex algorithms, but I don't think I've ever bought anything from Amazon without reading a review about the product from another user, or bought stock without going through several opinions written by more-or-less respected analysts.