Music added to Spotify is up to artists, labels and/or their management of what is available to listeners in any given listening region.
"Spotify wants all the world's music, and they're working hard on making this happen for you. However sometimes agreements can’t be reached with the artist or label or a change may happen in music ownership.
Spotify adds thousands of albums and artists are added every day. If you can’t find an artist you’re looking for, they may appear (or reappear) soon. In the meantime, feel free to contact the artist or their label to ask when they plan to be on Spotify."
If you have the music as local music files on your system, you can add those musc files in Spotify by using the Spotify desktop app and going to Preferences, scroll down to Local Files and toggle on where the local music files are stored at, or use the ADD A SOURCE button to navigate to the folder where your local music files are stored at. Once the Spotify desktop app adds in the local music files, simply go to in the Spotify desktop app in Local Files, scroll down to the songs, and then drag and drop those songs into the playlists you wish them to be in.
That doesn't answer why a whole album would be present except for a single song. Take the rap artist "The Game" on the album R.E.D the album in it's entirety is present save for the song "bang along" my favourite song on the album. I can see no logical way this makes sense, how am I supposed to listen to continue to pay for an incomplete service which doesn't even list full albums, and be expected to be satisfied?
Yea its crazy i tried to listen to juelz santanas what the games been missing and the 2 songs I want to here are on the list but not lit up so cant listen to them. Styles p gangster album daddys gotta get that cash is missing also
Artists are highly underpaid for their work via streaming services like Spotify (they average about $0.005 per stream) so in many cases it doesn't make sense financially to put a whole album up.
For example, the average song costs $3,000 to $30,000 to produce. To break even, it would need to be streamed 600,000 to 6,000,000 times. For big name artists this may not be a big problem, but anyone who is not a superstar, it's a tough business.
If you want the whole album, you should buy it so the artist can earn enough to keep making music. That's my thoughts as an independent artist debating whether to release my whole album, partial album, or just singles.
I hear ya though... Spotify is super convenient. Just thought I'd give you an artist's perspective.
Doing a little more research... I see estimates for a hit song can cost $75,000+. Thats only to MAKE it, not market it. Add about $1,000,000 for mass marketing and boom! ...you've got a hit song. Easy as pie ;)
That's likely why some artists and labels hold out... to encourage fans like you to buy the album, which you did! Respect.