Okay, more to the point, our economy is driven by love of wealth and love of power, not love of neighbor. Therefore we can expect it to be unjust. That’s the world we live in.
It doesn’t have to be so unjust. We can be made better, but it is not easy.
The OP asked what is a just wage. To answer that through the application of Christian principles in today’s world leads to certain incongruities and contradictions. It doesn’t quite fit.
The solution is not to declare injustice to be justice, or capitalism to be good, as some would have it. One only needs to look around to see that the economy falls short of goodness. Looking on the bright side, there is plenty of opportunity for us Christians to serve the poor – feed, clothe, teach, counsel, and so on.