A large chunk of the workforce does not. They depend on the paycheck, need to feed people that depend on them and in their case, the employer holds all the cards. They more or less must sign. Even if they have another option lined up, for them it’s probably the choice between bad or worse terms.
It's just basic supply and demand. A job that anyone can do is going to have a larger labor supply than a job that few people can do. Employer demand is also a factor. Right now truck drivers are getting very lucrative offers because demand is so high, despite the relatively low skill level. Also risk factors, especially risk of death, can drive compensation sharply higher. For example working on live natural gas pipelines or deep sea welding isn't particularly high skill, but the compensation is huge because it has a tendency to lead to death.
If those people don't want their kids in this situation maybe they should try being not poor. You feel me?
Hold a gun to someone's head and act like they have a free choice when they decide to do what you demand of them.
If you don’t want this to happen in your own life, then don’t sign such contracts. Leave other people to their own business. You are not their parent.