If anyone wants to learn more about the people and places in this world, I can think of no easier way. Just make sure you have on hand a lot of postcards of your own area. Thankfully the whole project is devoid of politics. About the closest we get to politics is to complain about our various postal services.
I have a beef with my own post office. The substitute letter carrier, not the regular guy, delivered a book to me on Saturday and jammed it so hard into my mailbox to make it fit, that the wrapper and the cover of the book inside were ripped. All because they did not want to return it to the post office and leave me a card that I had an over sized package. My regular mailman just brings any big packages to my door. But that takes time and is above and beyond service. A "substitute" feels no such duty.
Postcrossing requires a lot of trust. You send out random postcards hoping that eventually you will get some in return. Sometimes the mail system is rough on cards and they never reach their destination. Sometimes people get lazy and do not mail what they have promised or even acknowledge that they have received this gift in the mail. But despite these pitfalls, hope springs eternal and everyday people join the postcrossing family, from around the world. Although everyone is hoping to get a postcard from Greenland, those residents seem reticent to join the family of postcard swappers. Do they have postcards in Greenland? I imagine they are pictures of glaciers, which I hear are melting. More land is being exposed and so the livable areas of Greenland are expanding. Maybe there is hope for more Greenlanders! The people of Hameln did it!