[ss2f]

I agree with your observation that reduction to single 'causal factor' is delusional. You may want to check chapter 1 of Lisa Lowe's _The Intimacies of Four Continents_ where a possible answer to why US and Australia v African colonies differ is presented -- that you cannot understand colonialism and imperialism as atomic parts scattered around the world. They are all intimate, organized around ideologies of hierachies.