Why is whether the employer created it or not relevant? What matters is the fact that the employee is forced to work, or to starve. In the times of widespread slavery, a slave owner didn't create the system of slavery, yet nobody would disagree that the slave owner is exploiting the slave, for the slave has no choice but to be a slave, either to this particular owner or to any other owner.

It is not a consensual relationship, and at the very least it is exploitative, just as a prostitute who must sell herself on the street to make ends meet is being exploited - not by any particular person, but by the system perpetuated by the individuals who force her to sell herself in this way. When the only alternative is starving, I'm afraid to say that it's not consent when someone agrees not to starve.