Comment by FarmerPotato

I don't see much difference when you consider the condition of farming and mining slaves in Roman society.

Slaves were spoils of war since before the Republic.

Even if a slave had valuable skills, and were treated better, they had no legal recourse against a Roman citizen. Their owner could sell them like chattel, break up families (slave marriage had no legal basis) and kill them outright.

The highly skilled could enter into a kind of indentured servitude. That's a separate category.

You hear romantic stories about household servants gaining high esteem and a few being granted or buying their freedom. These were the exception, against the backdrop of menial labor.