I often wonder this about the measurements. I most definitely do not have a 24 inch waist. It's 26 or 27. Yet, a lot of the size 2s or even 4s say 24-25 inches.
Red, that makes a lot of sense about the pattern cutting, and I know nothing about sewing. But, I actually like the Gap jeans as I just discovered the fact they make petite sizes and sell them on line. I know that even if they feel tight at first, they will stretch. I've bought a couple of pairs of "jeggings," and some skinny jeans that I couldn't fit into in any other brand, because I couldn't get them over my calves or thighs in a size that fit my waist. With Gap, I can buy my regular size and they fit because of the stretch.