They were, and then there was NuBus, Apple's own floppy format, OS used a mix of Object Pascal and Assembly, Quickdraw, Quickdraw3D, NuBus, NetTalk,...
I don’t think those are good examples. The. ‘80s were an era of rapid evolution, in which about everybody had its own low-level stuff.
NuBus, being a standard predating it’s use in the Mac (https://en.wikipedia.org/wiki/NuBus) technically was more open than the ISA bus on the PC (https://en.wikipedia.org/wiki/Industry_Standard_Architecture: “The ISA term was coined as a retronym by competing PC-clone manufacturers in the late 1980s or early 1990s as a reaction to IBM attempts to replace the AT-bus with its new and incompatible Micro Channel architecture”)
In 1984, floppy formats were still changing all the time, so Apple picking something non standard for hardware that wasn’t used much by anybody else wasn’t unheard of.
Writing an OS in assembly was normal, too. Shipping graphics libraries with it wasn’t, but you can’t blame them for writing their own. What should they have picked? X Windows is from June 1984.
Quickdraw 3D, one could argue, should have been based on OpenGL, I don’t think it was clear that would be a winner on the desktop in 1995. Also, they started with usability in mind, supporting easy copy-paste of models working, something OpenGL doesn’t aim for (https://en.m.wikipedia.org/wiki/OpenGL%2B%2B did, but it started after QuickDraw 3D (and, like it, died))
AppleTalk, similarly, started with usability in mind, leading to the use of thinner cabling (at the time, ethernet cables had a diameter of almost 1 cm https://en.wikipedia.org/wiki/10BASE5, required terminators, etc), easier configuration (plug in the cable, and you’re good) and also predates the realization that TCP/IP is the winner, networking wise.
