California, Here We Come! - S4-E13
Revealing mistake: The Pontiac's glass windshield is gone when the car is loaded down with everyone's stuff, thanks to Fred's packing, and the windshield is also very noticeably gone when they all finally drive off. The rearview mirror, which should be attached to the windshield frame, is gone as well. (00:20:30 - 00:22:50)
Answer: There is no reason. It's a just a silly plot device, typical of the era. Women characters were often portrayed as making uninformed assumptions or decisions.
raywest ★