A more recent example is Communism where every country that claims to adopt it doesn’t do that

Huh? There is no country that has ever claimed to have adopted communism. The “Communist countries” are so-named because they are ruled by the Communist Party – similar to calling Canada a “Liberal country” because the Liberals hold power – not because they have actually achieved communism or believe they have achieved communism.

Those countries often claim that they are working towards post-scarcity (the precondition of communism), but that’s quite different.