I think the points that Ellyn makes illustrates how absurd the resistance is. I agree with the reason Patrick outlines is really where the problem is. IIRC, the book about the Afghan pilots said that protective underwear was made available but the soldiers refused to wear them. The same probably applies to the young race drivers, who want to keep with the macho image. There are increasingly more women race drivers, which I think is great. I'd bet that
they would wear protective underwear to avoid peeing in their fire suit.
When you see that TENA (or some other) is listed as a sponsor on the body of a NASCAR entry, then I'll believe that the stigma is nearly gone. Perhaps in 10 years as the demographic changes to a "country for old men" will we see more of a shift.
PS: NASA didn't like the term diaper, so they came up with MAG (Maximum Absorbency Garment). See
https://en.wikipedia.org/wiki/Maximum_Absorbency_Garment