Answer:
Because of the existence of certain types of market failure, employers can still engage in DISCRIMINATION and not necessarily lose profits.
Due to the existence of market failures like asymmetric information held by the employers, they can be able to discriminate in the wages they pay to employees such that they do not lose profit.
As an individual allocates their time, they face a trade-off between LEISURE and work.
An individual spends their time between leisure and work and they need to find a trade-off between the two that they are comfortable with because more hours allocated to one means less hours to the other.
Employers have some control over WAGES and adjust them in order to compensate for the danger or unpleasantness of a job and help contribute to certain types of market failure.
As a result of employers adjusting wages to suit the job characteristics or to entice employees, the job can contribute to market failure if the wages being paid are simply too high for that position.
Not all markets are perfectly competitive, due to the presence of UNIONS, which advocates for better salaries and working conditions on behalf of their members.
Unions campaign for their members to get better salaries and working conditions which might not be representative of the contribution of the job which leads to a situation where the market is no longer competitive because the tradeoff is not balanced.