History: In the 19th century, there was a small literate population able to read newspapers and magazines. This led to stores emerging as a mass commercial medium with in-store media allowing stores to easily communicate with immigrants and the illiterate. It developed into a competitive tool, with different stores showcasing their goods through windows, displays, and other methods. Success using the store itself as a communications medium was powerful. It was engaging and it was ultimately more successful than any other communications medium deployed by retailers before or since.
Source: In-Store Digital Media: How to reestablish Retail’s Role as a Mass Consumer Medium