eBay should encourage users to use ground shipping
Product Design for Sustainability
Artiom Dashinsky

Amazon isn’t saving any trees by any measure, but they have many examples where they try to optimize packaging and shipment options. Similar to your example here, another good one might be the shipping preferences on Amazon where you get money to select the “no rush” (ground) option. Also, many products are attainable at an extra cheap price if you buy them with a larger order (they prohibit one-off purchases of these select small items due to waste).