One of the most notable, and least savory, aspects of imperialism was systematic economic exploitation. The imperial powers saw the lands they occupied as little more than cash cows to be exploited for their mineral wealth and natural resources. Very little, if any, of the wealth extracted from imperial territories ever directly benefitted indigenous people. Instead, it was used to enrich colonial powers.
When erstwhile imperial territories finally gained their independence, it was invariably the case that their economies were in a damaged state after years of exploitation. This immediately put these newly independent states at a serious disadvantage to the powers who had exploited them for so long.
Although such states may have enjoyed political independence, they quickly found themselves having to enter into disadvantageous trade and financial deals with the world's richest countries. With little or no leverage, and with their economies almost ruined, states in Asia, Africa, and South America found themselves with little choice but to allow rich countries to dictate the terms of any future economic relationships between them.
Even today, the legacy of colonial exploitation lives on, with countries in the developing world left with little or no choice but to give generous concessions over trade and mineral rights to Western countries in return for tax revenue and the creation of much-needed employment opportunities.