That's a concept that might make sense, and it is something that I've heard from others over the years.

Except: The hypothetical perfectly-packed 53' trailer that leaves the originating warehouse is not the same trailer that delivers stuff to my doorstep. Things get sorted and re-sorted as they move along. It ultimately becomes random instead of optimized, and these random giant boxes take up a lot of space in local delivery vehicles.

Besides, the exceptions can be too exceptional to support any notion of it being deliberate.

It's difficult to describe the biggest box I've ever gotten from Amazon, except to say that it was too big to fit onto the seat of the recliner by the door where I usually put these things. I've received full-size, assembled, 1990s tower PCs in smaller boxes.

Inside of that exceptional box was just 3 ethernet cables, each 1 foot long, that cost me less than $1 each. That whole box could have been a brown paper envelope.