The networks were just switching to color en masse around the time that Star Trek came out and the penetration of color TVs was still pretty low--well under 50%.
Where I came from, although most families had a colo[u]r primary tv, if there were any secondary tvs (kitchen, bedroom,...) those were b&w up until around 1985.
This is accurate. When I was growing up in the early 80s I loved Star Trek. We had 4 TVs but only one of them was color. That was reserved for my Dad (who hated Star Trek, but loved football). I grew up watching the original series on Black and White... and the lighting was quite perfect for that, even if it was pretty mauve and absurd in color. Also worth noting that the color TVs at the time tended to be very low contrast compared to what we have now. So heightening the shadows and highlights made perfect sense.
As a side note, my mom was an accountant at Paramount who handled residuals for Shatner, et al. She briefly dated Harlan Ellison before marrying my father, which might have explained his aversion to Star Trek and my banishment to the Black and White TVs while watching it. (When I was twelve or thirteen and got really into Ellison's fiction, she got alarmed and told me Harlan was "a creep" and left it there).
The upshot was I got to go onto the TNG set when I was a kid... which was both wildly exciting and sort of disappointing as it wasn't an actual starship. All I wanted was to be Wesley Crusher.
But yeah, we watched TOS in b&w.
[edit] even funnier side note, I used to tape Star Trek TOS on reruns while I was at school so I could watch it later on the color tv. I had figured out how to work the VCR timer by the time I was 11 or so. But there weren't any blank VHS tapes lying around. My dad had a collection of 100 or so tapes of movies from TV, with commercials and everything. Down near the bottom of the stacks were a bunch of tapes labeled "dirty movies 3,4,5" which I thought just meant they were bad recordings. So I was like, I can record over those, they won't notice.
My dad apparently tried to play his porn tapes and found a bunch of star trek videos and came to my bedroom in a rage, but then couldn't explain to me why "dirty movies" didn't mean "bad VHS recordings". Took me awhile to figure out since I'd never actually watched whatever was on the tapes first ;)
Even later! My grandparents still had a black and white "portable" in the kitchen in the early 90s. My friend (who was wealthy) still had a black a white portable that my friend's sister would watch soap operas on in the mid-90s.
We had a B&W portable that lived on top of the refrigerator but was dragged into the dining room to watch Wheel of Fortune and Jeopardy for weeknight dinners. The TV itself was from the 70s, but we were still using it in the early and mid 90s. It still had paint dried on its case from when my parents watched it while painting the rooms of the house.
