Until quite recently in the show's timeline, Kansas City, where the events of Episode 5 take place, was ruled by FEDRA. FEDRA is essentially what's left of the U.S. government, and it operates with impunity in most of the quarantine zones in cities across the U.S. FEDRA was particularly brutal to those living in Kansas City, though, abusing the citizens they were supposed to be protecting for nearly 20 years.

That's why Kathleen, the leader of the citizen resistance movement in Kansas City, ultimately leads an uprising to overthrow FEDRA and retake control. As we see in Episode 5, part of that effort involves tracking down and punishing those who worked with FEDRA before the citizen takeover. Those who worked with FEDRA, turning in their neighbors for plotting against the government, were known as "collaborators."