The number of seats is limited. The number of shrimp (for all intents and purposes) is unlimited. Actually, the opposite is more precisely true. The marginal c

The number of seats is limited. The number of shrimp (for all intents and purposes) is unlimited. Actually, the opposite is more precisely true. The marginal cost putting one more person on a plane is minimal, compared to the fixed cost of the flight. The marginal cost of one more shrimp correlates more closely with the total cost of shrimp.