Final answer:
Joe's scenario of receiving a lower salary due to a disability despite equivalent qualifications represents employment discrimination in the labor market, particularly related to disability status.
Step-by-step explanation:
The situation where Joe receives a lower salary than Janet based on his disability, despite having similar education, training, and work experience, is an example of employment discrimination. Employment discrimination occurs in the labor market when employers pay workers with the same economic characteristics different amounts because of characteristics such as race, gender, religion, age, or disability status. Public policies such as requiring equal pay for equal work attempt to reduce these earnings gaps, but disparity still exists in practice due to various factors, including historic and systemic issues.