system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why the hell does a society of wizards who can teleport as a cantrip bother with mail delivery via owl?

Owl Mail is slower than Methuselah running up hill in January while knee deep in molasses.  Why doesn't everyone just wave a wand and send their mail directly to the recipient?  Hell, why use letters at all instead of just whipping up some magic mirror skype chats?

It's almost like the wizarding world is actively trying to have a less efficient society.
gpt
Post Owls are ridiculously fast, just think of the times the ministry or Dumbledore send him letters, like it barely took them minutes to responds to events that were happening to Harry. Then if you factor in an owls natural ability to locate a person on name alone regardless of where they are and it makes much sense to use them for deliveries. It also helps that since they dont apparate you can use them to send mail to places protected by enchantments, like Hogwarts.