It’s drums because there are multiple drums involved.
That’s why keyboards would also be more appropriate. It (pretty much always) refers to a keyboard rig.
I can’t recall ever having come across an album that mentioned ‘keyboard’ as a credit.
Same as I can’t recall having come across just ‘drum’ as a credit.
If the musician only played one single keyboard, the credits will pretty much always define it to be a piano, a synthesizer, an organ, or whatever.
If an album says ‘keyboards’, which is very common, you can be pretty sure the musician played multiple keyboard instruments.
But since MusicBrainz doesn’t allow ‘keyboards’ and will force you to use ‘keyboard’, that information gets lost.
That is not good.
Every time I see a release in MusicBrainz that says ‘keyboard’, in my mind’s eye I see the musician behind a cheap 100 bucks white plastic Casio keyboard.
That is not good.
Also, MusicBrainz instruments bible says that ‘keyboard’ is always an electronic instrument.
But as we seem to agree, ‘keyboards’ on album credits is often a combination of acoustic and electronic instruments.
So MusicBrainz currently has no way to translate such credits correctly into the database.
(well, not without listening to the recording, looking at photographs, or making a telephone call to the musician)
That is not good, and it’s at least an error/oversight in MusicBrainz’ instruments guidelines.
Well, I think I have been repeating myself. And looking at previous lengthy threads about drums, idiophones, instrument families, this seems to be a very difficult topic.
Maybe it’s the worlds of musicians and theorists colliding here?
(b.t.w. I also came across ‘shakers’ being a percussion instrument.
Maybe we can trade keyboard to keyboards, against shakers to shaker? 