Why are immigrant countries all developed countries?

There seems to be no corresponding concept of "immigrant country" and "non-immigrant country" in English. Because almost all countries allow foreigners to obtain green cards and apply for citizenship, but their enthusiasm for immigration is different, but there is no distinction between immigrant countries and non-immigrant countries. \x0d\ As for the concept of "immigrant country" in Chinese, my understanding is that it is a developed country with active immigration policies and diversified population sources. Famous immigrant countries are the United States, Australia, Canada, New Zealand, Singapore and so on. \x0d\ But hundreds of thousands of people from China immigrated to Japan, but Japan is generally not considered as an "immigrant country". The reason may be that the source of Japanese residents is relatively single and the immigrant population accounts for a small proportion of the total population. \x0d\ As to why not many foreigners immigrate to China. Personally, the reasons are as follows: \x0d\ 1. The standard of living is not enough to attract nationals from other countries to move in. \x0d\2。 Environmental and food issues. \x0d\3。 There are walls. Foreigners lost contact with their circle of friends when they came to China. \x0d\4。 Special system.