system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do most countries have different outlet prong formats, and there isn't a universal one?

my girlfriend is going to australia tonight and shes running around trying to find the correct adaptor so it got me wondering...
gpt
Electricity infrastructure was set up before international travel was cheap and easy, and before portable electronics. Electrical devices started off big and hard to move, and people didn't travel much anyway, so nobody really wanted to carry electrical things with them from country to country, and there was no real need to all use the same format.