The idea that market transactions are inherently impersonal was nicely outlined in David Graeber's "Debt: The First 5000 Years". In summary, market transaction

The idea that market transactions are inherently impersonal was nicely outlined in David Graeber's "Debt: The First 5000 Years". In summary, market transactions are final, in that you once a the goods exchange is complete you will have no further obligations to the other party. This property is very useful, and makes our goods exchanges very easy, but they are still inherently impersonal. There are other forms of goods exchange that do not have this property, which he discusses in the book. Of course, market transactions being final doesn't mean that no further relationship is _possible_, but that relationship forms outside of the market system.