Ask HN: Why don't companies trust each other like they demand of us to them?

Take Windows 10. Microsoft is demanding we trust them to store our data and usage patterns with them. Yet at the same time, they don't trust others. Why doesn't Microsoft just use Amazon Cloud or Google Compute for their own services instead of building up their own Azure? Why doesn't Microsoft just promote Dropbox instead of demanding the use of OneDrive? Why doesn't all of Microsoft's websites just use Google Analytics? Why isn't Microsoft just using Gmail for it's own mail system like Google recommends to millions of others?

If not Microsoft, why doesn't Google trust other companies like they demand of us? Why did Google create Android instead of trusting Apple's iOS for mobile? Why doesn't Google just offload their entire servers to Amazon Cloud instead of trying to manage all those data centers? Why doesn't Google just use Oracle and Microsoft Windows Enterprise instead of building their own system? What is Google so afraid of that they don't want to use software (and now hardware) created outside of Google?

Apple. Why is Apple creating it's own map software instead of just letting everyone use Google Maps and Gmail?

I'll stop here because I can go on and on with nearly every single tech company which demand we trust them.

To conclude, I've read hundreds of articles and comments saying we should trust the companies otherwise we're the ones who are wrong. And these are from highly respected organizations with millions of viewers! "There is nothing to worry about." Many of them say "this is the future".

Yet those same companies, for some reason, don't trust other companies with the same data they demand of us. Why? Why does it looks like Microsoft, Google, Apple, Amazon, and so forth are the ones stuck in the past? Why don't they trust each other like they demand of us to them? Isn't this the future?