This below is windows 11 consistency, within their own os context menus. I am not even starting on the fact that window decorations there too are a non standardised mess.

I agree that lack of UI consistency is less than ideal, and very real in Linux, but let's not pretend that this is a main issue stopping people from migrating (from an equally inconsistent OS)

Edit: okay, WTF Windows is now even worse?!?

Always has been. At least since NT. Company culture encourages features and discourages fixes. Thus it got framework after framework.

It's sad that this gets downvoted to hell. As a MacOS user who appreciates beautiful UI, this is a major pain point for me on Linux. And yes, Windows is the absolute worst at this.

How is a kernel meant to enforce anything about UI?

I think GUI development should favour server-side decorations for consistency's sake, but this is more of a cultural thing with what application developers are choosing to do, rather than anything "Linux" can do about.