There are so many comments here from people not understanding why anybody would ever want their history to be public, or shocked that that's the default...

Here's the thing: you get to type whatever you want, so you turn everything into jokes. Because it's public, you get to make up things that will embarrass your friend. Cryptic emoji. It's fun. It's just silly. When you pay back friends at a bar, you can browse their history and make fun of them.

None of the other payment platforms are fun like that!