[Beltiras]

You are making an apples and oranges comparison. On the one hand you have something that theoretically (and sometimes provably) is checked by people besides the project maintainers. You are absolutely right, but even taken your framing OSS OSs are orders (yes, plural) of magnitude more trustworthy than even older versions of Windows than 10. The privacy violations in 10 are large enough to make the system unusable by anyone that works with sensitive data (be it code, medical records, personal information, proprietary information etc).