Amazon: We hire no extra workers for Prime Day, it's just like any summer sale

Professor of Supply Chain Management Dale Rogers says Amazon is testing its expanding delivery system, a smart test pre-holidays.

In this post on Yahoo Finance on July 11, 2017:

“I think they’re going to build internal capacity, but they will also continue to grow external capacity,” Rogers said. “Wall Street won’t like it if their return on assets become much lower. It makes sense for Amazon to outsource part of them and have a mixed delivery strategy.”