Anybody long enough to remember Unix from the beginning or even just the last 25 years... which is a tiny percentage of this site... should know that a unifying Unix or Unix "tradition" as noted in a follow-up comment is a pretty much a myth. The tradition is whatever system you grew up on and tribal biases you subscribe to and the only true Unix traditions are mostly trivialities like core shell syntax and a handful of commands, and a woefully underpowered API for modern purposes. And long option names are definitely not part of any tradition.
Myths like "everything is a file" or file descriptor is complete bollocks, mostly retconned recently with Linuxisms. Other than pipes, IPC on Unix systems did not involve files or file descriptors. The socket api dates to the early 80s and even it couldn't follow along with its weird ioctls.
Why are things put in /usr/local anyway? Why is /usr even a thing? There's a history there, but these days I don't seem much of anything go into /usr/local on most Linux distributions.
It's also ironic to drag OS X into a discussion of Unix, because if there was one system to break with Unix tradition (for the best in some ways) -- no X11, launchd, a multifork FS, weird semantics to implement time machine, a completely non-POSIX low-level API, etc, that would be it.
All this shit has been reinvented multiple times, the user-mode API on Linux has had more churn than Windows -- which never subscribed to a tradition. There's no issue of lack of familiarity here, the original Unix system meant to run on a PDP-11 minicomputer only meets modern needs in an idealized fantasy-land. Meanwhile, worse is better has been chugging along for 50 years while people try to meet their needs.