There are moldable bumpers/foam for this application. The foams can also be made from bio materials such as mycelium (which can actually be grown/entrained to shape) or that puffy corn starch that can replace “packing peanuts.”
Combine with cardboard and paper tape and you’ve got a pretty well compostable shipping container. Landfill neutral.
That's answering a different question, which is how to get away from foam to better materials. The question asked was why aren't they shipping reusable bumpers, which is because there's a market disincentive to, since it costs more, works worse, and doesn't help the company that makes/ships with it.
Combine with cardboard and paper tape and you’ve got a pretty well compostable shipping container. Landfill neutral.