I credit Apple with single-handedly destroying classical music metadata across the entire streaming music space, despite their good intentions in hiring musicologists and setting standards.
The one good thing Apple did was to enforce the use of a "composer" contributor role, which they can then display prominently (most, but not all of the time, as does Spotify), as well as standards for properly crediting other contributors (performers). However, even on Apple Music, and on Spotify, there are contexts where the composer does NOT display, so it's not always useful even there.
Where they screwed up, royally, was messing with the existing "track title" and "album title" fields in counterproductive ways. One problem is that even Apple and Spotify don't ALWAYS display the composer name in all contexts, and nearly all the other platforms (except IDAGIO) either only make the composer name available as a drill-down to track details, or don't make it available at all. Thus, the ONLY reliable place to put the composer name (so that it is actually seen by users on every platform in all contexts) is at the start of the track title field, like "Beethoven: Symphony No. 5..." (The album title is not useful for this purpose, since so many classical albums are compilations of works by multiple composers, or increasingly may have a "marketing" name beyond just a list of the pieces included.)
The problem is that Apple's metadata standards (in their style guide) FORBID use of the composer name in the track title - they will reject the entire album if you submit any tracks which include the composer name (or really aggregators and distributors will reject it first to avoid having Apple reject it, which is one reason many aggregators won't submit traditional classical music to Apple in the first place, because Apple's nonsensical standards are such a PITA to deal with).
This leads to endless listings of "guess the composer" classical tracks (including, often, on Apple Music itself), which is totally worthless if you expect classical to be anything other than random background music.
(In a similar problem, since the track title is the only place to put the movement name, if the track title gets too long, the movement information may not display in many contexts, again even on Apple Music itself. But Apple wants all the, often-redundant, metadata, including key and opus number, which lengthens the track title unnecessarily. So now you can have lists of tracks with names like, for instance, "String Quartet No. [blah] in [blah] [major/minor], Op. [blah], but no composer or movement name in sight!)
If you get clever, and want to submit separate releases to Apple (and IDAGIO and Spotify) vs other platforms, you've just doubled your work as a record label, and also might not then be able to use the same ISRC codes for the tracks or UPCs for the albums (now that the metadata technically differs, they're considered "different tracks" and "different albums"), meaning you'll get two separate sets of streaming data for every track and for each album as a whole, which is kind of annoying and may hurt your chances of appearing on sales charts (if they don't properly combine the different data into one).
As for album titles, Apple's standards include something like "if the album consists of a single track, must be identical to the track title." (Their other standards for classical album titles aren't any more useful or less inane.)
Of course what Apple should have done from the beginning was to enforce the submission of proper "work name" and (where appropriate) "movement name" fields (in addition to the "composer" role), all of which could reference standard lists of known composers and works (and the works' constituent movements).
Then their standards for the track title might only say something like "a clear, concise, and unambiguous summary of composer, work name, and movement name, preferably no more than so-and-so characters in length, formatted generally like so" (ie, " Composer [last name only unless initials are needed to avoid ambiguity]: Work name [flexibly named in your language of choice, so long as it is concise and unambiguously identifies the particular work]: Movement number/name"), and enforced no standards on album titles at all. Then in their app, they could choose to display the composer name, work name, and movement name IN PLACE OF the track title in certain contexts (such as while playing the track), if they so wish, and leave the track title as a useful summary for display in lists (which often display no other metadata, and may have a limited number of characters displayed), or for useful display on other platforms which don't support the composer, work name, or movement name fields in the first place.
Apple seems to have let musicologists (with experience only of academic use of the relevant information) make their decisions regarding classical tracks, without any reference to how the metadata would actually display in different contexts ON THEIR OWN PLATFORM (sometimes the composer doesn't display even on Apple Music), let alone how the same metadata would be used on every other platform the same tracks were submitted to. Since nobody wants to submit multiple releases for different platforms, we have had a decade or so of composerless classical works submitted to streaming platforms around the world, thanks to Apple.
