It only makes sense if you were going to (hypothetically) do something with the pesos. Let's say you bought 100 pesos worth of bananas when you hopped in the ca

It only makes sense if you were going to (hypothetically) do something with the pesos. Let's say you bought 100 pesos worth of bananas when you hopped in the cab. Then, when you got out, before you paid, you sold the bananas. Because of inflation, you got more pesos for the bananas (say, 150 pesos), and still only had to pay 100. So at the end of the trip you have 50 pesos you wouldn't have had if you had to pay at the beginning (and couldn't buy your bananas).