I suspect that black is simply the cheapest, but now that the only people who buy vinyl are hipsters who have more money than sense, they can easily recoup the cost of the different colors of vinyl by increasing prices.
Does anybody remember picture discs? Are those still around or have made a comeback, respectively?
ETA: to add something more on topic: I seem to remember that the audiophiles back in the days sneered at non-black records because allegedly their sound quality was inferior. I don’t know if there was any substance to this.
Speaking as a (former) radio dj, I hate the colored vinyl albums. They are notoriously hard to cue.
You think it’s hard finding the start of a track on a black album? Try blue, white, or (God forbid) clear. Yes, clear. One of the artists we played all the time at my college station released his songs on see-through vinyl. Even better, the bastard put his 45’s on 12 inch discs instead of the usual 7 inch ones. You’d get the song all ready to go and then play it at the wrong speed because the damn thing was a 45, not a 331/3.
Records were black because it was the cheapest and simplest way to color the disks. Other colors were possible, but it meant you had to stop production to clean the equipment, which slowed output.
Dave Mason’s Alone Together (1970) was multicolored.
I was convinced. I had a picture disc of Who Are You? and the title song sounded lousy compared to the same recording on “The Kids Are Alright” soundtrack. I never bought a colored or picture disc after that.
I picture MP3 as a pale blue, AAC is orange, WAV is bright white, OGG is a dirty gray, FLAC is green, and Apple’s AIFF is a rainbow of primary colors, like a beachball.