• Nothing that some customer could have bought is removed by jumping a turnstyle.

      Nothing? Not even the fuel required to transport the extra weight of somebody who hasn’t paid? Not even the wages for the employees who conduct and maintain the trains?

      You can argue that the amounts are miniscule, sure. But “miniscule” does not equal “zero”.

      • When you’re paying, you’re not buying the fuel nor are the salaries directly affected by one person is paying for riding a train.

        What you’re describing is called “marginal cost” and reducing this is the reason why the economics of any large scale business is actually working. You could argue with these marginal costs, but you’d be entering a completely different model/domain of economics. And no one uses this model which is abstract/non-abstract in any aspect that happens to make your point valid.