You have taken me completely out of text, but I do disagree with you on a lot of this issues. The Great Britain has suffered more for enslaving other nations and one look at the country's economic history will just tell you how it has been negatively affected by slavery, colonialism, etc. The notion that some people tend to have that the west is rich now because of actions of the past is pure fallacy. Even the arguments you made about Bangladesh is completely invalid. Privatisation is the sole reason for Bangladesh's economic growth right now, which has been severely hampered by past socialist/leftist governments. And I strongly believe if the markets were more deregulated and some government laws reduced, Bangladesh would have a thriving economy. Look closely how Singapore's economy was deregulated and free markets reforms played important role on its economy. And I strongly believe India's recent growth has been due to their shift in more freer market reforms.
If you have been to USA or UK, or any western country, you will notice that the poorer areas like detroit are almost always run by a left leaning parties. For example, it was the idea of the left leaning parties to introduce the minimum wage law in order to help the black community, but according to a research, the minimum wage rather caused more unemployment.