Actually, I was reading what an old West Texas guy had written elsewhere...
Panties, sometimes called 'step-ins,' began to be manufactured in the 1930s. Within a short time they were equipped with elastic rubber waistbands. Back then elastic was not long lasting. Also, rubber was in short supply in WWII. Even after the wars with Germany and Japan were over there was the war to keep underwear up and tight.
Women of this era planned to that time when their unmentionable might do the unthinkable, and land on the floor. The considered course of action would be to step out and away. No way that could be any worse than for the proximate world to watch you pick up panties that most likely would not stay up. One should realize the person had probably been struggle to keep the underwear up for a while. She underwear fall to the floor, the relationship was irreconcilable.
This situation happened to my wife's mother in a grocery store in the 1950s. She was talking with the store manager about a missing item. Fortunately her grocery basket was between him and her and he never saw the fall from grace. He walked away and there was no one else on the aisle at that time.
Because men wore pants, you could at least get to a restroom, if not home. Once elasticity was gone, the underwear was pretty much hopeless.
Many women went to pant suits after WW2, just to avoid this crises.
Improvement in elastics along with combining them with fabric pretty well eradicated the problem by 1960.
