The same thing they did before the employer moved into town.
Which for the most part was a $2.48/day sweatshop or near starving on the street which is why ...
When a company builds a new factory in a low wage country, ($2.48/day) workers beat a path to their ($2.50) door because it beats the alternative.
You are correct. This level of voluntary servitude where the alternatives are no better, except the ones involving dying of starvation, cannot technically be called slavery even though in practical human terms there is little if any difference.
So does this make it acceptable to abuse people?
Does this make it acceptable for Wal-Mart, Adidas and others to say, "Your safety, your life, is not worth the few pennies in per share value our millionaire shareholders might suffer if we treated you with the respect due a real human being"?