The main way to make this argument is to say that it is exceedingly difficult for the government to determine what constitutes an unfair job. This is something that is beyond the ability of the government to judge.
It is one thing for the government to protect workers from things like unsafe jobs. It is much more possible to decide in an objective way what jobs are unsafe. We can look at things like workplace injuries and deaths and say that a job is unsafe. It is also clear that workers should not be subjected to unsafe conditions while at work.
By contrast, things are very much more difficult when it comes to the issue of fairness. There is no objective way to determine (for example) whether it is unfair for a fast food restaurant in New York City to pay its employees $8.00 per hour after they have been working there 2 or 3 years.
Because of such issues, it does not make sense for the government to protect workers from unfair jobs. It is simply impossible to determine what jobs are unfair when it comes to things like wages or opportunities for advancement. Therefore, (we can argue) the government should not try to make these decisions.