It is a labor to task the faculties of a man — such problems of profit and loss, of interest, of tare and tret,(8) and gauging of all kinds in it, as demand a universal knowledge.
17 The service and tax that governors impose on people get more and more heavy.The escaper is punished by very inappropriate ways.Many people are banished to the frontier of country or killed.
经济学百科 The Economics Book (Big Ideas Simply Explained)
The ancients lived in societies where labor was composed largely of slaves, and medieval Europe ran on a feudal system, where peasants were protected by local lords in exchange for labor or military service.
So even in that amendment, there's hints that this thing, enslavement, or if you want to call it servitude, and those are two different things legally, but whatever they are, they aren't simply gone.
Extreme poverty, illiteracy and a lack of skills guarantee that workers and their families readily provide such labor, even if that means they are bonded for life.