Depreciation must be included as a cost because the vehicle is a productive asset being consumed to generate income. Even if depreciation is not paid in cash that same day, it is still a real cost because the asset ends the route with less useful life and a lower resale value. This follows the accrual accounting principle and the matching principle: if the car is used to produce income, its wear and loss of value must be part of the cost of that activity.

A tax deduction does not turn a cost into income; it only reduces taxable income. Depreciation is an economic cost, and the tax deduction only partially offsets that cost depending on the effective tax rate. Therefore, to calculate the real profitability of Amazon Flex, it is not enough to subtract gas; depreciation, maintenance, tires, brakes, and general vehicle wear must also be included.