Why do different countries have different electric outlet plugs?

There are 15 different kinds of electrical outlets around the world. One standard would be more convenient, but no one wants to change theirs.

Ac Power Plugs And Sockets: Most Up-to-Date Encyclopedia, News & Reviews

Japan Voltage, Frequency, and Plug Type: Guide to Plugging In - JapanLivingGuide.net - Living Guide in Japan

Mains electricity by country - Wikipedia

Types of Electrical Plugs: Types, Uses, Features and Benefits

What Plugs Are Used in Different Countries?

Electric outlet. Different type power socket set, vector isolated icon illustration for different country plugs. Power socket. World standards icons set. Switches and sockets types set. AC power Stock Vector by ©artskvortsova

Plug & socket types

Premium Vector Power socket icon set. world standards for different country plugs. illustration.

Electricity Guide: Voltage & Outlets by Country

Why Do Different Countries Use Different Plugs?

Why different countries have different plugs?, by DesignNest Team, DesignNest

Type G electrical plug type

Power Outlet Guide: Which Plug to Use in What Country