This is all why I am implacably opposed to the concept of internships.
I understand what you mean, but I'd like to offer another point of view. It is from my own personal experience and obviously does not cover all types of internships.
I've been involved in internship programs in three very different roles--as an intern myself, as an employee working with interns, and as a political constituent.
As an intern, during my last two quarters of class before graduating from University, I worked a telecommunications company. The company accepted that school comes first--my work schedule would alter as much needed and as often as needed for me to attend to school classes and have study time. They also trained me on tools that I'd need to do my work, which was paid time,
and which was also education that the University accepted as course credit. The university worked with the employer to ensure that the training was for tools and topics similar to those that I would have learned in class. The cherry on top is that during the internship they offered me a full time position to start after I graduated with no break in employment, and with all benefits and seniority back-dated to the start of my internship as if I had always been a full-time employee. It was also a much higher salary than other companies offered me, I assume because this company already knew I was a dedicated worker and was already trained on their specific tools, whereas I was an unknown greenhorn to everyone else.
It was an enormously positive experience for me, and beneficial to all parties involved. The school got to boost their job placement stats and freed up a seat on campus for any classes I would have been in. The employer got labor, a chance to "test drive" someone without full time commitment, and eventually they got a full-time employee they liked. I had a job that paid me about three times more than what most typical hourly part-time jobs would, I earned work experience in my chosen field, I received paid training that counted as course credit, and I got a great full time job right out of school.
As an employee (at a different company), I observed that we hired interns, we paid them fair wages, we worked around their school schedules (if needed), and if we liked them we offered them full time positions. If we didn't like them, we didn't need to fire them or lay them off, because the internship was inherently temporary like a contract worker.
As a political constituent, I've gone to my state capitol and lobbied on my own behalf (protesting, showing support, and testifying before senate committees). At the capitol during the school summer break there are hordes of unpaid interns referred to as "pages". Pages were basically high school students performing relatively unskilled administrative assistant tasks. I don't know much about the details of the job, but I did have lunch with a page, and I asked her why they were volunteering for politicians. She said that it would look good on a college application and it would count as college credit for civics class. But she also said that the main idea was that they got to be around powerful and connected people. If you were a good fit, you'd end up on their staff and having those connections would be an advantage for a future political career. Because the supply of pages was far higher than the amount of future staff positions, pages were extraordinarily competitive with each other, and so they "busted their asses off" so-to-speak.
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To summarize, my experiences were counter to the stereotype that internships have. I'd say that internships in the private sector were fantastic in every way, and I'm glad that I was able to take advantage of the university/business internship program.
However, in the state government, internships seemed a little bit dirty. Politicians are essentially trading a slim possibility of future access to their inner circle and influence in exchange for highly motivated free labor. I suppose from a cynical point of view that this actually
is good training for someone wanting a political career in the USA.