In fairness, there are some enterprising vendors who find ways to get rid of flies.
Pom-poms. These fluffly colorful balls of ribbon, wool, straws and papers are usually for decoration. Pom poms with long cut-outs are used in cheer dance. But enterprising vendors used them to manually ward-off flies too.
Those who want to automate the process used cheap ceiling fans with paper (or plastic) cut-outs at least six inches in length pinned on each blade.
Another way to ward off flies is to fill a clear plastic bag with clear water. Hang the bag from the ceiling. The movement and refraction of light by water will baffle and scare flies away.
Do you have other ways to shoo away insects? Share them here.