The men of the Peltzer family are menaces to society. They bring non-native, invasive species into their town, and cause possibly millions of dollars of damage to their tiny town by failing to follow the instructions they were given. The father gets the species by ignoring the responsible adult and listening to a child.
Mrs. Petzler, on the other hand, is a badass. She takes out three gremlins in close combat.
Also: Why doesn’t Billy know the story of Kate’s father? Didn’t they grow up in walking distance of each other in a small town? I would think that story would be a local legend.