To be fair, there has always been difficulty in sorting classical music by category.
Era, country, ensemble/solo, solo instrument. How difficult is that?
Well like any spec... once you get to encoding it, exceptions may be discovered.
Faced with the
fact myth that Vivaldi wrote the same concerto grosso 500 times, and by necessity some of them were in the same key, one may in desperation end up with a playlist titled something like "This one dammit".
One might put a composer's acknowledged cataloger's abbreviation in metadata for certainty of reference to a particular work, e.g., BWV827 for a JS Bach work, FP 61 for a work by Poulenc and so on.
Sometimes there's a good reason for manually compiling lists. At least iTunes lets you construct both smart and manually constructed playlists, and both can be given desired names that "even Siri" could launch on command.
One day I bumped into the link below by accident and was duly impressed. It's literally just a list of works featuring the oboe, although it's part of a huge undertaking with live links, the IMSLP (International Music Score Library Project).
What struck me immediately was the fact that
some of the work titles made no reference to the oboe at all. Some human being knew that
hautbois means "oboe" in French, and someone knew that Jean Gabriel Prosper Marie's
Chant Pastoral is a work for oboe and piano or orchestra.
There was a moment in time when all I wanted was to listen to one track of Coldplay vs one track of Joe Satriani (during the time when a question of plagiarism surfaced). So a simple playlist and then ask Siri to play "The Chris Versus Joe Question".
Sometimes all I want to know is whose soprano I prefer in some solo in a song cycle. That usually ends up being a manually constructed playlist as well since it's faster in that case than a smart playlist.
On the other hand maybe all I really want to know is how much Poulenc I have on hand and I don't even want to play any of it, just refresh memory of some aspect of my collection. At that point I could not care less what Apple or a distributor called the genre of the relevant works, but I could end up pretty annoyed back in the early 00s when I sometimes had to look at more than "composer" to get a correct smart list.
What I'm coming to here is that we can ask distributors to police genre tags but that it's unlikely "genre" is the be all and end all of categorizing music for any of us. Everyone may have need of particular --even peculiar-- groupings from time to time, and the genre tag is not going to be of much help even if "Classical" got busted down to levels like "Baroque keyboard" and "German expressionist opera".
"Classical" music aficionados may have lots of reasons past genre to mess with the metadata on their digital downloads of music depending on their general interests and sometimes on specific subgenres, say operas or cantatas. And certainly some related reasons not to let iTunes organize the files. It's not likely you want a bunch of opera tracks stashed by "
artist, album, track", and if you ever want or need to move that opera's files someplace else, good luck rounding them all up if you had let iTunes work its artist-centered magic on their locations.
I know Poulenc's Dialogue of the Carmelites pretty well but damn if I remember the names of all the soloists. So it was track by track get info, find file... and in fact that mess was what made me take charge of my music's metadata and also of where my iTunes files reside.
One way to get around limitations of the tags (once you've fixed them up) is to use smart playlists to organize temporary or permanent arrangements of works one may want to listen to in a certain order for whatever reason. The editing rules for smart playlists let you not only drill down by reference to any tags, but also understand constructs like "contains" versus "equals", as well as logical selectors (AND... OR) in order to end up with a set of tracks you could give a name to that Siri would be able to launch.
Does that sound like work? Sure, but it lets us be the boss of the music we have on hand. In the end we get what we pay for, and sometimes our own labor is the best part of a good investment. It doesn't resolve search problems with online catalogs for streaming purposes,,,, and I think that's probably an intractable problem until we get more ways to "tag" stuff we don't download, aside from stashing tracks in playlists.
Again, I enjoy using Apple Music in my own way, which is to compare specific performances in order to help me select a CD for purchase. Usually I can find in Apple's catalog what I want to work with in order to do that. Otherwise lol I resort to Amazon or Spotify. Either way my pretty transient AM library is less focused on genre than some of my other iTunes libraries, but I've long since given up expecting any commercial entity to tag music in the way I might elect to do. That doesn't mean we shouldn't pressure distributors to clean up their act a little, and ask the middlemen like Apple or Spotify to insist on that too, by requiring that the labels at least identify composers (!) in metadata, and by consulting artists on how they believe a release should have its main genre identified.