Some of this is also due to poor QC at the manufacturers. I went out pants shopping just this past weekend and tried three of the same pants of exactly the same

Some of this is also due to poor QC at the manufacturers. I went out pants shopping just this past weekend and tried three of the same pants of exactly the same size and all three fit drastically differently, from absurdly small-couldn't-get-it-over-my-thighs to so ginormous they looked like clown pants and had a hugely saggy crotch. And it wasn't a cheapo store either. But I had to mindful that there was a reason I was able to find decent work slacks for $20. Pant sizes should really just be "guidelines" unless you are getting something custom tailored.