The first reason is that my waist is not particularly large, any you people are fatasses. The underwear you sell is sized accordingly.
The second reason is that you can't try on underwear. I mean, you could try them on, probably. But then you run the risk of being asked by the employees if you opened a package of underwear, tried them on, and then stuck them back in the package. And nobody wants to find themselves there.
The last reason is that everywhere, every time I look at a package of underwear, this fucker is staring back at me.