Expectations change over time.

But I also believe your recollection is erroneous or must differ by region because I was there as early as the 80s and computers sold without an operating system weren't common. If you were buying a PC clone in the 90s you could buy it without the Windows license, of course, but the default was to include it.

Even before PCs, computers typically shipped with BASIC, which was their operating system of sort. Macs, Amigas, they all shipped with an OS as well.