system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: if I buy something from another country, how does my country's postal service get paid?

Edit: I bought something from china for 20 cents with free shipping and it was delivered to my doorstep, how are they profiting?
gpt
By agreement between the members of the Universal Postal Union, each country gets to keep its own postage for international mail, even though the postal service of the destination country or any third countries through which it is routed must assist in delivering the mail. So if you're in the United States and send something to France, the U.S. Postal Service gets to keep all of that money. Conversely though, La Poste gets to keep the postage for mail going the other way. A few decades ago the UPU introduced a new rule, whereby countries that send much more mail to another country than they receive from that country will pay a per-ton amount to compensate that country's postal service. Once such imbalance exists between China and the U.S., so China pays the U.S. every year.