Amazon ships hundreds of millions of packages per year. The internet is filled with articles about the mass amount of packaging waste created by Amazon. It is a very real problem for landfills and recycling facilities but it is not unsolvable.

Padded envelopes and cardboard boxes do not need to be disposable items. They can be easily reused many times. Amazon has successfully created it's own delivery system that outshines all the others. There is no reason they couldn't pick up packages of clean flattened boxes and padded envelopes collected by their customers.

By providing a small reward for collected pieces they could turn it into endless publicity. People could earn points and save pennies on future orders. Schools and homeless shelters could collect packaging from the community to use towards buying supplies. This waste could be turned into a positive thing and probably save Amazon money. 

There is no reason for all those boxes and plastic envelopes to be discarded after one use!