I am not 100% sure why these forces still fly this old aircraft, but the only reason I can imagine is that all of these countries spend a significant amount of money on (self) defence as they are all in a (cold) war. As new fighter aircraft cost billions of Dollars, they will keep them flying with spares from the USAF who have thousand of these aircraft stored in Bonyards like AMARG. As an example Turkye and Greece don't like each other, South Korea does not like North Korea and Japan also does not like South Korea. Next to this, both countries also don't like China :) And offcourse we all know that Iran was not able to buy new aircraft since the Iranian revolution so they have to fly these old aircraft. Funny fact on the Iranian Phantoms is that they fly them with self made parts and modifications as the USA is not supporting them anymore since the 1970's. It is a rumour that they fly some of these with Russian engines.