Disappointed in Size/Quality Control

Disappointed. Size I ordered from Amazon is the size I always buy/wear from stores. The pair received, while marked as correct size ordered, were almost too small for me to even get on and zipped-up right out of the bag. I can't imagine how I would have gotten them on after a few washings/shrinking. They were made in Mexico, for whatever that is worth. I don't see the point in buying clothes online anymore if you cant trust accuracy of sizing, and if that isn't trustworthy, what can one conclude about quality of materials, workmanship, etc.?