Those who think that labor market under capitalism gives uncompetitive salaries (that is below that what market would give in equilibrium) are wrong. The salaries are higher than supply and demand in equilibrium would give. This is why people do not want to lose the job, because they are afraid that other jobs would pay less (meaning that they are getting more than equilibrium would give) or that they just become unemployed. This is also why there is unemployment - businesses prefer to have less work places and pay more, so that they get the best employees.

This is actually classical example where market (labor market) does not work as wished by market supporters (achieving no unemployment)- there always will be unemployment and at the same time there will be always unhappy people who are afraid of losing their jobs. But uncompetitive salaries is not one of the problems of the free labor market. Small salaries, maybe, but not uncompetitive.