Probably the average criminal just didn't think of nuts as being particularly valuable (even though they clearly are).
Wasn't there a case in Canada a few years back where someone stole a huge amount of maple syrup? That stuff is pretty pricey, too.
Edit: yep, $18 million worth. They were caught, eventually.
https://www.thestar.com/news/canada/2017/01/27/men-convicted...