Continuity mistake: After Herman breaks through the doors in the opening sequence, the underlying wood over the right side of the hole is plain plywood. When it's Lily's turn to come out, the wood has been stained to match the rest of the door, and Herman's outline is more distinct.
Revealing mistake: When the show introduction focuses on the front door, the Frankenstein sized and shaped cut out area can be seen where Herman is to make his appearance.
Answer: The comedic gimmick of both "The Munsters" and "The Addams Family" television shows in the 1960s was that both families were convinced they were normal and everyone else they encountered was odd. The Addams Family, for example, thought their "normal" visitors were mentally unbalanced because they always fled the Addams' weird home in panic. That was a running gag throughout the entire Addams Family series, so much so that easily half of nearly every episode was devoted to the predictably terrified reactions of their visitors (always accompanied by identical canned laughter). Meanwhile, in the Munsters' universe, the family thought "normal" people were physically deformed and even quite hideous. For example, the Munsters believed that their beautiful niece, Marilyn, was socially handicapped by her ugliness (the exact opposite of the truth); and, in the episode "Just Another Pretty Face" (S2E17), when Herman Munster was temporarily transformed into a "normal" person, his entire family found him utterly repulsive. The family's hidden revulsion to "normal" people was the running gag of The Munsters.
Charles Austin Miller