Installation Access Denied musings

I was trying to build an install file and test it on Linux.  It kept 
telling me 'Access Denied.'  I ended up having to chmod ugo:+w on the 
<mozroot>/components directory.

Curious, I tried to download some other stuff from mozdev.  Turns out I 
had to unlock the <mozdev>/chrome directory and everything in it (or 
something in it, anyway) to install xultris.

Seems like everyone running on Linux will have this problem.  Some 
postings from the Google archive were about similar problems.  Another 
solution is apparently to login as root and run Mozilla when doing the 
installation.

Not sure my point here.  Usability for average user?  Are there any 
average users on Linux who don't have root access to their own machines? 
  Should it even BE possible to install something to Mozilla on a 
multi-user system?

I have a Windows 2000 partition.  I started with Mozilla there.  I 
downloaded several games from mozdev with no problems.  Of course 
Windows has a somewhat different ownership model.  And my login has 
Administrator access.

Should there be user-specific Mozilla directories on some platforms?  So 
I could install as non-root user and it would go into a local directory 
and only be visible to Mozilla when I personally ran it?

Or is it possible for the install code to put up a "login as root" panel 
like some of the admin applications do?

Do other platforms (e.g. OS/X) have this issue, or is it just Linux?

mma