I'm much closer to the fat part of the bell curve than you, so you might not be aware that you are likely being denied half sizes in your shoes.

I used to call myself a size 13, but after I started running, either my feet shrank or I became more aware of the fit of my shoes, and I happened to find a size 12.5, which fit so much better.

Then I discovered that most shoes don't come in a 12.5 - they usually only do half sizes up to 12. And when a shoe is made in a 12.5, most stores don't carry it. So now I get to spend a lot of time trying to decide between a 12 that sometimes pinches (whee numb toes) or a 13 that sometimes is too loose (whee blisters) or looking for shoes that run big or small that might not be the style I want/need.

And most stores at least have size 12 and 13 I can try on; I can imagine the hell of finding not just size 16 but size 16 that fit right.