There's trust in the security sense, which yeah, you're stuck with the whole deal.
But there's also trust in the rely on sense. Which at least I try to compartmentalize. I can trust Microsoft (or Google) to make an OS I can rely on to run other people's apps. If Microsoft or Google want to provide apps, they'll be evaluated as they are, not with a bias because the OS provider shipped them.
I don't have a problem using OpenSSH, really. But I'm not going to use a Microsoft terminal emulator, unless it has some advantage over the terminal emulator I've been using for decades, when the Microsoft product has no advantage other than Microsoft included it with the OS so I can save a 3.5 MB download. Same reason I don't use Internet Explorer / Edge / new Edge or Windows Media Player. On a level playing field, I would never use those products (well that's not true, IE 3 was ok when it came out, IE 4 and 6 were good when they were new, but I don't have a time machine), so why use them because the field is unlevel.
But there's also trust in the rely on sense. Which at least I try to compartmentalize. I can trust Microsoft (or Google) to make an OS I can rely on to run other people's apps. If Microsoft or Google want to provide apps, they'll be evaluated as they are, not with a bias because the OS provider shipped them.