1. Ethnicity--colonies were broken into countries with no regard to ethnic groups. These groups differed before colonization and differed more during the colonial period. Many ethnic conflicts have occurred since, some resulting in genocide.
2. It is a more common language--the colonies were taught the colonial language and trade often continued with the European country that was once their ruler. Maintaining that language for trade eased the transition and makes trade more accessible.
3. Indigenous religions--these original religions still exist but differ greatly from one another. These religions were based in the tribes and colonies were a blend of many tribes. The European religions were often more consistent.
Because western democracies wanted to avoid war at all costs, wanted peace, hoped that a strong Germany would stop growth of communist Russia, wanted to avoid foreign affairs or felt it was not their business.