The glaringly obvious explanation is that people are buying the quantity they wish to eat. Why is it so unbelievable that people will buy 10 nuggets instead of 20 for the same price? I'm not going to take 10 extra nuggets and either throw them out or put myself into a food coma.

If we were discussing 1 vs. 2 cans of soup from the local grocery for the same price, of course everyone would buy 2 - you can save the additional can for another day. Here, we're talking about fast food that has to be eaten within a couple of hours. There is no "deal" to be had by buying a larger quantity if you're not willing to eat it.

The only sad thing about this article is the apparent inability to understand why someone won't stuff their face with more food than they can eat without making themselves sick and likely obese.