Is there really an issue with people being "extra" safe?
No, I don't think that's a problem. People can be as safe as they want.
I have a problem with people "preaching" safety rules as if they are the absolute end of the problem.
The "Four Rules" are often cited. While very good, these rules appear to be designed for safe gun
use. Inspections / cleaning / administrative chores are conspicuously missing.
So yes, all guns are loaded.
If you pick one up, the safe behavior should be, "verify whether it is loaded / unloaded before you do anything else." After all, if you are going to use it, you want it to be loaded. If you are going to inspect / clean it, you want it to be unloaded.
And, after the unloaded status is verified and the action open, it is
safe. Until you put it down. As soon as it leaves your hands, you can't really be sure about it. Someone else could have put a magazine in it and chambered a round. Unlikely? Sure, but the safest thing is to check it every time you pick it up, before you do anything other than treat it as loaded. And, of course, you maintain muzzle discipline while checking it.
I believe that is the spirit of "All guns are loaded"...they're loaded until you prove that they're not.
Further, to handle the problem of "others in the area" (such as at a range), it helps to have some kind of visual indicator that the gun is safe, before you ask folks to walk in front of its muzzle. This could be an empty chamber indicator, or perhaps just a requirement that the action be locked open or bolt removed. This is just a procedural expediency, to avoid the snafu that would result if you had everyone personally inspect every gun on the line.