Huh? I don't think that's true, there usually is some sort of structural elements inside of the package, meant to be thrown away (usually made with cardboard/paper), and all Ikea boxes definitively have lots of air inside of them, not sure what would make you say otherwise, unless it's some joke I'm missing?
A box that contained a fully assembled kitchen table would contain a lot more air. I think that comment just meant IKEA designs items that can be packaged into a minimal volume.
Ah yes, on second reading it's actually pretty obvious that is what parent meant and I was reading it too literally. Thanks for the clarification, that's certainly correct :)