The delivery program is part of Amazon’s plan to gain more control over how its packages are delivered and rely less on other delivery services, such as UPS, FedEx and the >US Postal Service. With these vans on the road, Amazon said more shoppers would be able to track their packages on a map or see a photo of where a package was left when they weren’t home.

https://english.alarabiya.net/en/business/technology/2018/09/05/Amazon-orders-20-000-vans-to-build-delivery-fleet.html

Sherman Act

This Act outlaws all contracts, combinations, and conspiracies that unreasonably restrain >interstate and foreign trade. This includes agreements among competitors to fix prices, rig bids, and allocate customers, which are punishable as criminal felonies.

https://www.justice.gov/atr/antitrust-laws-and-you