While shopping for a new pair of shoes a few weeks ago, my girlfriend asked me a question I didn't expect: "Which of your feet is larger than the other?"

I was caught off guard, simply because, as far as I could remember, no one has ever asked me that before. The first batch of questions back were, "Is that possible? Is that common? Do a lot of people have slight differences in the sizes of their two feet?"

Turns out it's not that uncommon. The size difference varies, and usually, it's not big enough for most people to notice when they put on shoes. But after having it pointed out to me, I did notice that the shoe on my right foot was slightly tighter than the one on my left. Apparently I have a bigger right foot.

So, just out of curiosity, why hasn't an online shoe retailer created a feature that lets people order a pair of shoes that mix and match sizes? It isn't everything, but surely somewhere in the long tail of fashion footwear there's a group of people who have enough of a size difference between their feet that they'd gladly pay for the convenience of two shoes that varied in size?