Amazon has already displayed abusive behavior in multiple markets, which is why they're constantly in front of Congress testifying along with companies like Google, Apple, and Facebook. In the case of Amazon, they're typically accused of using sales data to determine products to make under their own Amazon Basics brand, or using their massive capital to destroy competitors. The best example is Diapers.com, which Amazon eventually started competing with. However, Amazon started selling their diapers at a loss, which Diapers.com couldn't compete with. Due to this, Diapers.com went out of business, and Amazon just bought their assets.
Interestingly... what has Amazon done to us? How often do you look at something and think, "UGH! I have to
pay for shipping!?" I do eBay selling randomly, and there seems to be a preference for free shipping from people... even though my own auctions are priced so that it ends up hitting around the same cost as the free shipping auctions when you combine cost + shipping. On the flip side, free shipping is terrible for me as it artificially raises the value of the item. For example, a $105 free shipping auction vs. a $90 auction with $15 shipping will cost me more to insure (buyers almost never pay for insurance).
Did not realize Amazon actually had their own delivery trucks. Never seen one here. Wonder if they are only being used in some locations? Here it's usually still going through Canada Post or Purolator, but for the last mile it's often a local contractor or smaller shipping company like Canpar.
But yeah that could be concerning if they try to push out the bigger shippers, since nothing stops them from refusing to deliver anything that's not through Amazon.
It depends on where you're at. I've seen their semis around here, but we don't have Amazon delivery trucks. For us, Amazon uses a mix of UPS and USPS for the final delivery. (From what I've seen, Amazon's semis only feed into USPS though.)