For what it's worth, retail stores have been consolidating over the last several decades (and longer, but much less than thousands of years). If you want to sell your product at Walmart or Best Buy they're going to squeeze you on the wholesale price. Sometimes the savings get passed on to consumers, sometimes they don't.

It's not the concept of retail is somehow unethical, but certain stores are certainly less ethical (in how they treat employees, customers, environment, etc) than others, and some of those stores are very widespread.

Also the thousands-of-years argument holds up pretty poorly for a lot of things.