On another note, look how Apple both competes with Samsung and use Samsung parts for iPhones.
The industry is all about co- optition
Netflix also don't really have an option, outside of building their own cloud, since Microsoft and Google also have video streaming. It's a little different if you're a Sears or Walmart, and you're not directly competing with the other providers.
Same with Apple and Samsung. Sometimes you're stuck buying from competition because they're the only people making the thing you need. It doesn't mean you're happy about it or wouldn't jump ship if possible.
https://www.se-radio.net/2014/12/episode-216-adrian-cockcrof...
Just noting what I've seen from projects that I've actively worked on first hand.
(Also Walmart and Target are far from the only ones that do this, just using them as examples.)
The fact that Amazon is also a retail shopping site / now owns whole foods causes a lot of high end/large retail giants to NOT use AWS and actively have in their contracts that they will not do business with a company if AWS is their cloud provider.
There are exceptions, like if you stand up infrastructure specifically for the retail client that's against using AWS in another cloud instance (And I'm sure there are other exceptions out there).
But this is something that negatively impacts Amazon / AWS. I think ultimately though that's a business decision that they are welcome to make for themselves and I don't think really impacts the end AWS user.