The 1040NR is comparable to the U.S. 1040 tax return. This is going to vary from country to country, but I am putting my trust that those who are supposed to file taxes do so. In the U.S. all people who make money (there are, I believe, some thresholds) have to file taxes. Self-employed folks have to file taxes. Medium provides a 1099 to U.S. people and I do not know about what they do with other countries.