I think that is probably true for skilled workers, but the people delivering packages for Amazon in Chicago appear to be far from skilled. It's not that hard to find someone with a driver's license and replace them. Assuming Amazon has to offer similar benefits to Union shops, they will still save money. For instance, if Amazon offers its delivery drivers retirement benefits, you can rest assured there is no way in hell they offer a pension. On top of that, I can guarantee that Amazon won't hamstring its logistical flexibility by guaranteeing fixed routes.

This is even assuming that Amazon directly employs their delivery drivers. I know Google delivery uses contract drivers in Chicago. I wouldn't be surprised if Amazon has a similar set up in some places. It's pretty hard to organize when you are the driver.

Regardless, Amazon will fight tooth-and-nail to prevent unions from forming. They've successfully done so at their warehouses, and I don't see why deliveries would be any different. See this article by the NYT

http://www.nytimes.com/2016/05/17/technology/amazon-proves-i...