Even men’s jeans which are size by the actual waist and inseam measurement can be wrong.

They're not generally sized by the actual waist measurement. I wear 33W and my pants all measure about 36" around the belt line. The "waist" measurement derives from many decades ago when men wore high-waisted pants where the waist was a few inches smaller than the circumference around the hips, where waistlines are today. Men were also generally a lot fitter back then, too!