OpenBSD also has /usr/X11R6, where it puts the X stuff (their X distro is named Xenocara). This is another piece of legacy from back when you might want to have both /usr/X11R2 and /usr/X11R3. These days the X11R6 directory actually contains X11R7 shrug.
FreeBSD used to do this too, but got rid of it in FreeBSD 6 (I think? Maybe 7? About ten years ago).
That's because "packages" in the BSD world (at least openbsd) are considered third-party options, the base system is considered static. Linux distributions don't really have the notion of a static base system with "package" addons, the distribution packages are the system.
FreeBSD used to do this too, but got rid of it in FreeBSD 6 (I think? Maybe 7? About ten years ago).
Both systems install packages to /usr/local.