Comment by TeMPOraL

They're not doing them a favor. They're providing them a service.

Trust is a fundamental aspect of how the world works. It's a feature, not a bug.

Consider that e.g. your car mechanic, or domestic service (if you employ it), or housekeeping in hotel you stay, all have unsupervised access to some or all of your critical information and hardware. Yet, these people are not seen as threat actors by most people, because we trust them to not abuse that access, and we know there are factors at play to ensure that trust.

In this context, I see Microsoft as belonging to the cohort above for most people. Both MS and your house cleaner will turn over your things to police should they come knocking, but otherwise you can trust them to not snoop through your stuff with malicious intent. And if you don't trust them enough - don't buy their services.