My problem is that, for all the changes DoC made to vanilla mechanics, colonial relationships are still not realistically portrayed. Your colonies start with lots and population and infrastructure, the Trading Company industry boosts their yields further, and slave plantations and specialists help them produce things even more quickly, but all of these mechanics only apply to your colonies, not your core cities. They help your colonial cities to become good cities in their own right, easily comparable in commerce or production to your core cities. That is not how it worked in history. In reality, the relationship between European masters and their colonies was a one way road of exploitation and resource extraction. Europeans siphoned wealth and resources and values from their colonies to make things better in Europe, while only constructing the bare minimum of infrastructure necessary to keep the extraction of resources as efficient as possible. They wouldn't care to build an Observatory or a Factory or an Aqueduct or a University on some Caribbean island city. Put in game terms, they only improved tiles with resources on them, constructed only the most basic of buildings, and then set these cities to build Wealth, interrupted by training the odd military unit now and then, until their colonies inevitably declared independence. Atlantic slavery and the Trading Company industry should be mechanics that help boost European core cities at the expanse of colonies, not help colonies become decent cities in their own right as is currently the case.