Now I'm out of date by several years now, but outside of imports or "boutique" all batteries were made by one of two companies. East penn and johnson. They are unofficial partners and they pretty much determine who gets what in what state based on whether they are east or west of the Mississippi. That also includes the fancy optimas, interstate, delco, all of them.
Battery construction at scale is not a perfect science, and at the end of the process they are broken up into batches depending on final output. The various brands then get to pick a batch, slap their name on it and go.
Past that usually what determines the lifespan is luck of course, but mostly how it was stored. Many walmarts for instance store them outdoors in shipping containers or aren't cycled properly hence their bad reputation. Nothing wrong with the battery itself just how its stored, so in some areas where theres a good store people have good luck with them. Others not so much.
The leaking Battery in question was probably the result of someone stacking batteries at some point. Likely at the store itself when stocking the shelves. Odds are they wouldn't recieve credit for it when sent back, and that in most cases comes out of the managers bonuses which is based on several factors including warranties. Still bad customer service at the end of the day, but might explain their motivation.