Why isn't there a road for pedestrians?

I went on a business trip to North Carolina. A sales manager drove me to the nearest airport. He parked his car in economy parking. In this case, "economy" means it's cheaper than a parking lot which is adjacent to arrival hall and departure hall of the airport.
On the other hand, from the economy parking lot, we had to take a bus to the departure hall. It's convenient for us that there is a bus service. But, I wanted to take a walk from the parking lot to the departure hall to exercise.
There should be a road for pedestrians?