If anyone else is interested in some of the history of how we got here, Wikipedia has a pretty decent summary: "The 1874 treaty provided for the originating co

If anyone else is interested in some of the history of how we got here, Wikipedia has a pretty decent summary: "The 1874 treaty provided for the originating country to keep all of the postage revenue, without compensating the destination country for delivery. The idea was that each letter would generate a reply, so the postal flows would be in balance. However, other classes of mail had imbalanced flows. In 1906, the Italian postal service was delivering 325,000 periodicals mailed from other countries to Italy, while Italian publishers were mailing no periodicals to other countries. [...] In 1969, the UPU introduced a system of terminal dues. When two countries had imbalanced mail flows, the country that sent more mail would have to pay a fee to the country that received more mail. The amount was based on the difference in the weight of mail sent and received." https://en.wikipedia.org/wiki/Universal_Postal_Union#Terminal_dues https://en.wikipedia.org/wiki/Universal_Postal_Union#Termina...