"The pool of computer users has always been composed of 10% competent users and 90% clueless people."
Correct. Users should not notice the operating system. Users should run applications and programmers should write operating systems.
I find both Linux and OSX to be no better and in some ways worse than WinXP for the average user. Operating system updates should run in the background and be invisible to the users. Unfortunately, we have not reached that level yet with any operating system. In that regard, they all suck.
The only user intervention that Mac OSX asks for is (A) approval to install the update (which I think you can make automatic and background, but I don't), (B) clicking "OK" on certain licenses, and (C) typing an admin password for update privileges. I think (A) can be automated and (C) goes back to my point about security and ease of use. I think that password step is important to impose on a user. As for (B), that's legal nonsense but I'll agree it's annoying.
When the HP PC we had bought my mother-in-law's died, we gave her our old iMac (which was older than the HP PC) and I installed OSX 10.2 on it (I had just upgraded to 10.3 at home, so gave her the older OS so she could have the box and disks). A few months later, she mentioned that the update box pops up and she just clicks OK and does what it says and never had a problem. If my non-technical mother-in-law could figure out what to do without me even mentioning automatic updates to her, I think it's easy enough.