It's worth reading some of the papers where they discuss performance at counting tasks among the Pirahã. IIRC there were some people who seemed understood there was a difference in the quantity but struggled to quantify or articulate it; and there were other people who didn't struggle to articulate it at all, they just didn't bother with it or think it important.

"Number as a cognitive technology: Evidence from Pirahã language and cognition" http://www.sciencedirect.com/science/article/pii/S0010027708...