I would like to know this too! Say my team has 40 people on it. Every month at least, someone asks what do "40 people do?" and I take them through it 2-4 people at a time across several lines of business maintaining and improving lots of software.
Would be amazing to see some people break down their teams publicly!
Pandora acquired Ticketfly and The Next Big Sound a couple of years back so they're not just a music streaming company. I still can't tell you what they all do though!
I haven't looked at Pandora in a few years, but IIRC they were a lot like Groupon in that they had a huge sales force catering to local businesses - the type that would traditionally advertise on local radio stations.
It didn't look like a 2000 person company when I went to their office. They do a lot of random platform integrations / clients & testing themselves, which probably increases the engineering team size a bit.
No clue. But the answer to your question is being a public company. Market participants generally expect publicly traded companies (above a certain market cap) to have lots of employees.