How is the Documents folder locked to administrators?

People's home folders are their own. Other users on the system should not be able view or modify someone else's data. This is as intended. You should not be modifying the permissions to those other user accounts.

If you need to share data between users on the system, then you can place the data in the "/Users/Shared" folder which is why that folder exists. See the following Apple article for details and a read-only option for sharing using the "Public" folder within your home user folder.

Share files with others who use your Mac - Apple Support

FYI, the Finder has its own rules. And "sudo" and root are not absolute God options in macOS anymore due to the recent privacy & security changes in macOS over the past five years. There are permissions beyond root these days that cannot be circumvented. Trying to circumvent macOS behavior to get around the new rules will just result in a broken system since macOS does not like deviating too far from defaults.

Mikelis Bickis wrote:

Thanks for the lecture, but you did not answer my question. It is possible to share folders across users without using either the Public or Shared folders. I have many such.

And what is wrong with those options? We cannot help without knowing why the easy & official methods are insufficient for you.

I should be able to set up my computer the way I want.

Then macOS is not what you want to use. Apple decides how macOS can be configured & used. And Apple is getting more aggressive in limiting options. macOS has been moving towards an iOS format for years now. Think about what you can & cannot do on your iPhone & iPad.

I wanted to know how MacOS puts a lock on the Documents folder, since it does not seem to be using unix permissions. And why "Get Info" says everyone can read, when in fact they can't.

I did explain in my previous post. Apple is hacking on every new privacy & security related feature in order to attempt to hide these things from view. Some of these restrictions are baked into the core OS now with no way around them. If iCloud is enabled on any of those user folders, then that will affect the permissions and even the location of the data.

HWTech wrote:

People's home folders are their own. Other users on the system should not be able view or modify someone else's data. This is as intended.

This seems to be only partly true.

In my Sequoia system 15.7.3 the only folders in the /Home folders of other Mac users that are protected from viewing by my main admin account are the following: Desktop, Documents, Downloads, Movies, Music and Pictures. A user created folder inside any one of those is also inaccessible.

However, a user created folder saved within /Home folder itself, on the same level as those noted, is not secured by default on my Mac. I can freely open and manipulate any files saved within.

I'm sure I can manipulate the permissions of those folders using Terminal commands to disallow access from other accounts, but I wouldn't know what the command(s) might be.

This behavior is the same for me as far back as 10.15 Catalina. In fact, you can see a hint of that in the author's original post.

D.I. Johnson wrote:

HWTech wrote:

People's home folders are their own. Other users on the system should not be able view or modify someone else's data. This is as intended.

This seems to be only partly true.

In my Sequoia system 15.7.3 the only folders in the /Home folders of other Mac users that are protected from viewing by my main admin account are the following: Desktop, Documents, Downloads, Movies, Music and Pictures. A user created folder inside any one of those is also inaccessible.

Yes, that is correct. I'm actually surprised Apple has allowed that behavior, but it is probably due to the "Public" folder feature & this being the easiest way to implement it. Since Apple does not automatically show the root of the home user folder in Open/Save dialogs or in the Finder, the average user probably doesn't store things there anyway (may be Apple's thought process).

I knew I should have rewritten my post so that would not be brought up or I should have addressed it directly, but I was being a bit lazy today. Hoping no one would notice (should have known better) ;-)

Very likely, the enclosing home folder ("Macintosh HD > Users > (your login name)") is set up so that "everyone" has "No access".

Interestingly enough, although my "Public" folder is inside a home folder that has "No access" (for everyone), the "Public" folder has "Read only" access. The Public folder also has the "Shared folder" box ticked off, and I would guess that box might be controlling other permission mechanisms beyond the "rwx" bits – ones that can override the "No access" setting on the enclosing home folder.

Looking inside the "Public" folder, there is a "Drop Box" folder which does NOT have the "Shared folder" box ticked off, but which allows "Write only (Drop Box)" access for "staff" and for "everyone".