The GNU/Linux (or Unix) filesystem hierarchy makes backups so much easier. The utter lack of architecture under Windows is what makes backups so difficult.
Under GNU/Linux, a user wants their personal stuff backed up? $HOME. As a sysadmin the local installation stuff? /usr/local. A decent systemwide backup? /etc, /root, /boot, /var/stuff, /home, /usr/local, plus a list of currently installed packages and/or versions. You're 100% at that point.
Over-the-net backups -- that's an option. It's convenient, but it's not a full solution, and the expense (particularly for multiple versions or historic backups) are prohibitive.
MS Windows backups are a PITA? Blame the [link|http://www.microsoft.com/|fucking vendor].