That increases the volume of each item- sometimes significantly. That impacts storage density, but it isn't the only issue. I know everyone loves to complain w

That increases the volume of each item- sometimes significantly. That impacts storage density, but it isn't the only issue. I know everyone loves to complain when Amazon sends a too-large box for one item, but sometimes you order seven items and get a perfectly packed box. If everything is inside yet another box, that gets really hard to do. Plus, that's a lot of extra cardboard to pay shipping rates for. Plus, lots of vendors (FBA or normal) just wouldn't do it. The labour costs of adding those boxes adds up. Imagine if every pack of 3 pens needed to be individually boxed.