I guess it's more that it is difficult to ensure freedoms when people stay 'voluntarily' and don't speak out. There are similar stories about Chinese clothing factories based in Italy (thus: close to Chinese prices but "Made in Italy" labels). Workers without any locally relevant language skills are brought there, housed in Company housing, eat from canteen/company shops with produce they know, etc. Hard to fight if all the formalities of labour law are respected and the employees do not speak out against abuse/actual reality of implementation. Very similar to how U.S. companies, in particular the slaughterhouses are known to work, with often irregular migrants employed for their wonderful exploitation potential. You won't speak out if you think you'll be deported and can't suppor your starving family back home... And of course even much worse is known from the seafood sector, where notably Chinese vessels essentially enslave south east asian workers - where are you going to go when locked on a tiny boat...?
https://www.newyorker.com/magazine/2018/04/16/the-chinese-wo...
https://ww.fashionnetwork.com/news/made-in-italy-by-chinese-...
https://www.newyorker.com/magazine/2023/10/16/the-crimes-beh...