EU did have slavery
I still remember my history teacher teaching us about the famous quote "If they don't have bread, let them eat cake"
Again, I question your "mis"-understanding of history. Yes, in one sense the feudal system created an underclass of people that were essentially slaves but you miss the essential difference between modern day slavery and the feudal systems.
Feudal systems existed in both Europe, Egypt, India and Asia, particularly China. They arose as a way that the strongest of warring factions could effectively assert control over all the warring factions by granting them exclusive rights over territories, resources, and people. The page you cited makes reference to same. So, yes, the people were essentially treated like slaves but were not like true forms of slavery, like...
From the earliest times in recorded history conquered people were forced into slavery, the women raped and forced to have children, partly to supply labor for the winning party and partly to ensure that the the conquered society was watered down and destroyed. But, this is again different from...
Modern slavery - the practice of capturing people against their will, removing their rights, and forcing them to work for others against their will. While the USA is perhaps the most famous example, it's by no means the only one, including South Africa and Australia. The UK banned slavery in the British Empire (completely by 1843).
Slavery is still rampant in the world today, focused in India, Asia, and Eastern Europe primarily. However, sex slavery is also rampant in South and Central America, with women being brought to the US, along with those from China and Easter Europe. Houston is the common gateway.