Indeed, and good food for thought. The fungibility is a feature both of these products being commodities in general, and of their quality being measurable. Whe

Indeed, and good food for thought. The fungibility is a feature both of these products being commodities in general, and of their quality being measurable. When measuring quality is cheap and easy, the risks for a defector are high. When measuring quality is expensive and/or difficult, the risks for a defector are lower, and the defector's incentives may therefore be comparably greater.