>Slavery effectively disappeared in most of Christian Europe towards the end of the Middle Ages, because the Church opposed keeping Christian slaves.

It disappeared because it was replaced by indentured servitude on the low end and restriction and tax on who could do what trades on the high end. Because the lords own a huge fraction of all the farmland. So this is very much a "you're nominally free but you're gonna be share-cropping your old master's land" situation for the former serfs. An improvement, sure. But not nearly as big of one as the history books tout.

Lucky for them that didn't last very long until the black death made labor way more valuable so a lot of the rules got eased up and once that unleashed a bunch more productivity at the margin, well there was no going back.

>Most peasants were nominally free but tied to the land, with obligations towards whoever owned the land. Peasants farmed land owned by the local lord and paid rent with labor. And if the lord sold the land, the peasants and their obligations went with i

I'm not saying they're equivalent, but there's a very good comparison to most professional licensure to be made here.