Interns working on behalf of others (that is, interns need to pay relevant fees to obtain internship opportunities) is a common phenomenon in some industries and regions. The main reasons for this phenomenon are as follows:

First of all, the imbalance between demand and supply is one of the important reasons for interns to work part-time. In some popular industries and fields, internship opportunities are relatively few and the demand for internship experience is very high. This has resulted in fierce competition for interns. Some internship units take advantage of this imbalance in demand and supply and require interns to pay relevant fees to obtain internship opportunities.

Secondly, some internship units and organizations have profit-driven problems. Some commercial internship units or intermediaries may provide internship opportunities and at the same time make huge profits by using interns to work part-time. They can charge fees to boost their own profits without regard to whether the interns are being paid fairly and properly.

In addition, the imperfect legal protection and supervision of interns is also one of the reasons for the phenomenon of interns taking part-time jobs. In some areas, the legal system for the protection of interns is imperfect, and regulatory agencies are not strong enough in enforcing the law. This allows some internship units to take advantage of this legal loophole and charge intern fees.

Although it is a common phenomenon for interns to work part-time, it does not mean that it is reasonable and legal. Internship is a stage that is conducive to students practicing their skills and improving their professional competitiveness. It should be a period when students put in their efforts and get rewards. Working on behalf of employees not only violates the essence of internship, but can also easily lead to infringement of the rights of interns.

Therefore, in order to solve the problem of interns being paid part-time jobs, all parties need to work together. First of all, the government should strengthen the supervision of the internship system, formulate relevant laws and regulations, and strengthen law enforcement to protect the legitimate rights and interests of interns. Secondly, schools and educational institutions should pay more attention to internship education, actively guide students to participate in formal, fair, and legal internship activities, and improve students' awareness and understanding of internships. Finally, enterprises and internship units should also abide by relevant laws and regulations to ensure that interns can conduct internships under fair and legitimate conditions and provide them with reasonable remuneration and treatment.

To sum up, although it is a common phenomenon for interns to work part-time, it does not mean that it is reasonable and legal. In order to solve this problem, the government, schools and enterprises need to work together to strengthen the supervision of the internship system and protect the rights and interests of interns. At the same time, it is also necessary to improve students' awareness and understanding of internships and choose appropriate internship opportunities. Only in this way can internships truly play their due role and promote students' growth and development.