You state that the method would exclusively apply to the industrialised nations, and that is true. However, industrialisation is highly imperialistic (as imperialism is the highest form of capitalism and industry at first exists alongside capitalism) and as a result it will spread. For instance, take the industrialisation of India by the British Empire during the 19th and 20th centuries. It is natural for nations to industralise; otherwise, they would be far too behind in terms of technology and living condition. Also, previously-industralised nations would exploit non-industrialised nations and bring their culture and industry along. Certain conditions must be met for unions to spring out.