I trained as a designer and pattern maker when dinosaurs roamed the earth...most of the products were skiwear, golf and tennis.
1. Patterns for Canadian women had a 10" drop/difference between bust, waist and hips.
2. Patterns for the Californian market had a 6-8" drop/difference between bust, waist and hips. I made more room in the belly area, but I also had a size that was specifically built for pear shapes.
I used to make back waist length longer for my US customers (standard plus 1/2" and slightly shorter for CDN (standard minus 1/4").
My customers and I thought it had to do with age of customers, younger in Canada, older in CA.