Yikes! "This means that you don’t need to do anything to have copyright over your works." But you DO need a copyright notice to collect damages for infringement. Without a notice, the most you can get is an injunction to stop infringement. "Often, source code files repeat the file name in the file itself." So you can tell which file when printing, or when viewing through a broken web interface.
I doubt it would be worth the time and money of litigating in court to collect damages on a copyright case anyway unless you're Google or Microsoft.