Gus and Mike have both been shot. However, the personnel at temporary medical facility they found themselves in only focus on saving Gus. Jesse is frustrated by this because Mike and he are very close. Nevertheless, the doctor points out that Gus is the priority because he is the one paying his salary. This is also visible in our current medical system. Specifically, those who have the ability to pay often receive priority and extra-quality healthcare, which may not be equitable, but may be, perhaps, efficient.
See more: incentives, health economics, health care, cost benefit analysis, efficiency, equity, fairness