This is taught in microecon 101. https://en.wikipedia.org/wiki/Price_discrimination https://en.wikipedia.org/wiki/Price_discrimination Or in any basic market

This is taught in microecon 101. https://en.wikipedia.org/wiki/Price_discrimination https://en.wikipedia.org/wiki/Price_discrimination Or in any basic market where you have to haggle for everyday goods such as food markets in poorer countries.