An intern can only be unpaid if they are not doing productive work and you have a trainer with them. Most unpaid internships are illegal already, but the interns don't know they can/should report it.
If you are an intern in a railroad you can move cars around the yard all day: you can move them to a loading dock, or to make up a larger set for a train, but at the end of the day you must move them back. However if any of those cars are moved to the dock are loaded/unloaded, or the larger train they just made leaves the yard, then they did useful work and must be paid for that.
>>An intern can only be unpaid if they are not doing productive work and you have a trainer with them.
I mean yes, but like you yourself acknowledged - that's a completely meaningless law. No intern is going to report this, because young people are just happy to have a job, no one wants to destroy their career right at the start. I myself was in that exact same position when I started - as an intern, my contract specifically said I can't be doing any productive work. Of course I did anyway. And I'm sure it still happens in every industry, because.....why wouldn't it. That's why I think unpaid internships just shouldn't be a thing at all, anywhere, unless linked to vocational schools that oversee them as a training programme.
If you are an intern in a railroad you can move cars around the yard all day: you can move them to a loading dock, or to make up a larger set for a train, but at the end of the day you must move them back. However if any of those cars are moved to the dock are loaded/unloaded, or the larger train they just made leaves the yard, then they did useful work and must be paid for that.