Does he mean like old mining or lumber towns where the companies would pay in scrip and extract even more from the employees with the high markup at the company store?
They can only extract "even more" if employees don't look at how big the markup is before signing up for the job. You can't get ripped off unless at the point of the gun, or lazy.
Or have no other way to feed yourself?
Then that isn't the problem of 1 employer but a systemic problem.