> They undoubtedly have a large number of developers working on apps for every platform
Yes, if they were at the cutting edge on every platform and constantly adding innovative new features, that could certainly explain 500 of the 9000 employees.
But that still leaves 8,500 employees unexplained.
Developing the software is easy part. Handling and negotiating contracts and licensing agreements for all their music and podcasts (and advertisers) all across the globe is probably the hard part. Plus of course all the marketing, support and related tasks.
Still. There's only ~200 countries, and a good chunk of them either isn't worth having any presence in (no need to negotiate licenses for Somalia), or is so small and has similar laws to surrounding countries that they'll be treated as one bloc by the publishers you negotiate with anyway (all the Pacific statelets e.g.).
Between that and the ability to just contract local lawyers, 45 to (realistically closer to) 90 employees per (relevant) country is still a lot.
Also, spotify outsourced 90% of their support to their community (designated "star" members). There's no hotline either, so no call centres to run, or anything else personnel intensive. (And you'd outsource that anyway, realistically.)
Yes, if they were at the cutting edge on every platform and constantly adding innovative new features, that could certainly explain 500 of the 9000 employees.
But that still leaves 8,500 employees unexplained.