Unpaid internships are wrong. Normally the ugly underbelly of the finance / economic industry, this is creeping into the traffic and transport consulting industry.
If people do work for you, you need to pay them. Obviously their pay scale should reflect their experience and abilities.
I have seen some great paid internship programs that benefit the company more than the intern. It’s our duty to mentor, teach and expand interns ability, not getting “free labour”.
Note : When I googled this topic, google said “did you mean slavery”. My 2c.