DRM doesn't control your PC, it controls what you can do with files (usually through encryption via an app) and these streaming platforms are part of publicly funded libraries; they have a vested interest in not fucking up people's computers.
I don't know where you got the idea that DRM could become root user of your PC, but I think you should go research what DRM is, how it works, and why people are often against it. I think you're conflating DRM with anti-mod/cheat software, a kind of DRM, and that specific form generally has a fraught history with kernel-level access.
But you shouldn't fear DRM simply because it's DRM.