system
A chat on subreddit /r/wallstreetbets
human
The crux of my argument is still valid. Their costs are relatively fixed due to how they operate and extra packages, even if low priced, are a benefit to their bottom line. 
  
 Also, that may not be the case with Chinese packets, but for other contracts it's definately in their best interest to get the deliveries even if its at a lower price. This is something they do for Amazon and others.

gpt
just because the mailman stops by your house everyday anyway doesn't mean the costs to move millions of extra packages around the country everyday are nonexistent