Loyalty is a great characteristic to have in a dog. Humans should put a bit more thought and skepticism into their devotion to employer, country, party, religion, etc.
Exploiting loyal people seems to be accepted in society and we simply blame those individuals for being gullible. Whereas the exploiters get rewarded for their successful exploitation and learn that exploiting others is the best way to get ahead in life.
Educating the exploited or potential exploited seems like a more impactful action if the goal is to reduce the number of exploited.
Whereas continuously exploiting others requires a mental illness such as narcissism. Perhaps by focusing on the exploiters we can reduce the damage they do to others.
We don't really protect workers from that nor do we financially punish the exploiters, in fact many of them go on to be very financially successful. And as a society we have simply accepted burnout as being the fault of the individual who did not do enough to protect their work-life balance.
Problem is, there is no realistic way for that group to be able determine if what they are doing is exploitation or a perfectly fair trade without the worker telling them. That is why the onus falls on the worker. Only the worker knows their situation.
If the worker happily shows up and doesn't make it clear that something is wrong, one has to assume that the trade is considered fair. That is what the information available is telling.
At the very least we should mandate that overtime is compensated to a degree that represents the cost to society of burnt out workers who require healthcare or exit the labor force entirely.
However, the topic of discussion is about blaming the exploiters. Laws to try and help prevent exploitation does not speak to that.
Contractually preventing a worker from talking to other employers, hindering price discovery, may be exploitation, but one would know about it before entering into the contract and would only do so if they are okay with it. So long as the worker is able to talk to other employers, then they can learn just as much about the market as you are able to learn when talking to other workers.
That said, even if said contract was signed, it is unlikely a court would uphold such an obligation, especially when there is nothing offered in kind. They generally do not take kindly to contracts that completely remove one's ability to stably earn a living. The state doesn't want you to become its problem.