When we look at cost curves, often we notice they have a U shape which is the result of two opposite effects on the same driver. For example, the quality cost curve and the logistic cost curve.
Quality Cost Curve
If we put the quality level on the x-axis, from 100% defect to 100% perfect, say 1 to 10 in terms of quality level, the cost of achieving the different quality levels increases as we approach perfection. Something like this: