Yes, this issue with multi-item listings is so prominent and long-standing that I simply must assume it is a deliberate anti-user decision by ebay, though I can

Yes, this issue with multi-item listings is so prominent and long-standing that I simply must assume it is a deliberate anti-user decision by ebay, though I can't think of a good reason why. I just know that if they wanted to fix it they could have by now. All it would take is making "quantity" a core part of the data model for each listing, enabling search by quantity and sorting by price-per-unit.