I can see why they use the foam 'nuts in boxes even when they contain grain... They need to take up the dead space with something. Otherwise, with how UPS, FedEx, etc. handle the packages, you'd probably have grain spilled all over the inside of the box...
Different vendors use different packing materials. Some use recycled paper, others the air filled bladders, others the foam nuts... I think it has more to do with what they think will do the best job for how they pack things. In the end, it all does just as good a job...
I DO wish that you could put the foam materials out for recycling, and get them picked up. Last time I tried that, they left it all on the sidewalk... So now I have to put them into trash bags (which we have to pay extra for, since they're special for the town) and put it out at the curb. If I get a decent amount of deliveries, I space the packing materials out over a few trash days... Or I take them up to my mother's place, where they don't have to use special bags. Or, when working, I'll toss them into the dumpster there (as long as no one minds)... I could use the dumpster near where I live, but the police station is within eye-shot, so I'd rather not do it... Plus, I believe it's for use by the town hall only...