There are token rewards for successes and punishments, sometimes extreme, for low productivity. If a slave is seen as having no worth to the endeavour and cannot be trafficked, they will sometimes be killed as a warning to the others that productivity is expected.

It’s a horrific and brutal scenario that pits victims against victims. In many ways, the targets have less to lose than the victims targeting them.

"...workers at KK Park are subjected to 17-hour workdays and are frequently spied on, tortured, and threatened with murder when attempting to flee the compound.[11][17] Passports and cell phones of workers were confiscated to prevent unmonitored communication with the outside world. The complex includes supermarkets, hospital, restaurants and hotels to form a closed community.[citation needed] Illegal organ harvesting was also reported to take place inside KK Park.[4] KK Park victims could only leave by paying a "contract termination" fee which is calculated by the inflated cost of transportation and how much money the victims earned for the scam companies."

https://en.wikipedia.org/wiki/KK_Park

Jesus. It had never occurred to me that the front-line people perpetrating these scams could be enslaved themselves.