system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it still so expensive to call internationally, when i can download free apps and do it for free?

Seems like charging per minute is a little outdated. 

EDIT: Thank you all for the thoughtful, well written responses. I genuinely appreciate it.
gpt
Because the way the systems work are different.

When you make a phone call, it gives you a dedicated connection from you to the person you are calling (which is known as circuit switched) and making that dedicated circuit for you can be expensive.

When you use an app, it flings packets of your voice call in to the aether, and if they don't all arrive or arrive out of order, the programs are designed to cope with that.  This is known as packet switched.

You can look at it as the difference between a rifle shot and a shotgun blast- with the rifle, you are making one long distance connection that takes some effort to produce.  With the shotgun you are flinging a lot of little bits at your target and enough of them should hit that it gets your message across.