Steve, what you listed are not what my Werner ladders weigh. For example, my 16' is 18 lbs, not 31. Again, my 28' is 38 lbs, not 56.
Maybe you're only looking at type 1A aluminum ladders. That load capacity rating is unnecessary for what I do. I scurry up and down ladders a few times a day. If I was over 300 lbs and perpetually carrying 4 bundles of shingles up to the roof, I might need it.
Never had a defect that would need warranty coverage. I've replaced ropes and a couple moving parts after a couple decades of use. 4 years ago, I replaced my most used 28' after 31 years only because of its appearance. I still use it around the homestead.