Have you been near some sort of news in the last years? Corporations using windows get hacked regularly and they are far off from having everything in a database somewhere. You have no fucking clue. What you are describing is the dream of corporate security newbies, but no big corporation let alone some state government is anywhere close to that.

They have massive shares, where all the people can read and overwrite everything, they open all attachments directly on their machine and click away all warnings without reading them. (Who needs USB if you can mail malware directly?)

This is hell and in Germany dozens of smaller or bigger government networks were hacked and massive amounts of data encrypted last year alone.

This is because enterprise manages security properly - layered, minimum perms to perform a task, etc.

Apparently Microsoft itself isn't Enterprise?

I’ve never seen a virus or malware on a machine in enterprise...

Change Healthcare - https://www.msn.com/en-us/money/companies/change-healthcare-hack-what-you-need-to-know/ar-BB1kvg2t

MGM Grand - https://www.cnn.com/2023/10/05/business/mgm-100-million-hit-data-breach/index.html

HP Enterprise - https://apnews.com/article/russian-hackers-hewlett-packard-enterprise-microsoft-sec-breach-cozy-bear-d4e88ded0a47d010216e11f41132f72c

Here's 12 more - https://www.kaspersky.com/blog/ransowmare-attacks-in-2023/50634/

Users simply lack permissions to change stuff, so malware lacks it too.

Oh something is lacking in your world and I'm not talking about permissions.