I’ve noticed that every product I’ve bought in the past year with a zip-lock seal is destroyed with common use. I actually think the zip-lock itself has gotten stronger. The bag rips before the seal opens on half the bags now and whenever I try to opens bags I had no issues with before, I find myself stretching/warping the plastic before the seal eventually opens.
It’s pretty frustrating and I am seeing it across many products. Cheese bags, storage bags, snacks etc…
The point is… before you could reuse the bags MUCH more often, now I’m blowing out gallon ziplocks after 2-3 deli bought and home diced vegetables uses. The zipper is stronger like OP says, but the sides are tearing more easily.