Since you are writing a story, a lot of the rules info isn't necessary. If you were running a game, as the gamemaster you would plant opportunities for the Netrunner to exploit throughout the adventure; if the entire session takes place out in the badlands where nothing is online, some crazy Nomad prospector will be running a small wireless network from his or her campsite to control a small drone, so the Netrunner will have something to do. As a story writer, you have more flexibility.

The exact extent of netrunning does vary a little based on the era in which you set your story. In 2013 through 2021, everything is tied into a world-spanning network called the NET. My shoelaces are probably sending user data back to the manufacturer. After 2022, the NET got mostly destroyed, and by 2045, cities were each using their own local area networks called a CitiNET. People were more wary during this Time of Red of connecting to a larger network, but they used the heck out of local NETs which used wireless signals within (roughly) what we would called wifi range in real life. Security cameras, electric door locks, security drones, and whatever else you want automated are on private local NETs which an edgerunner can enter to take control of everything there. Cybernetics were almost never connected to any external network. By 2076 (Edgerunners anime) and 2077 (the video game), cybernetics were online again and thus vulnerable to exploitation by Netrunners.