The whole idea of interns, is as training positions. They are supposed to be a net negative.
The idea is that they will either remain at the company, after their internship, or move to another company, taking the priorities of their trainers, with them.
But nowadays, with corporate HR, actively doing everything they can to screw over their employees, and employees, being so transient, that they can barely remember the name of their employer, the whole thing is kind of a worthless exercise.
At my old company, we trained Japanese interns. They would often relocate to the US, for 2-year visas, and became very good engineers, upon returning to Japan. It was well worth it.