I went back and in my original post I said sell and that was wrong. Mea Culpa. In the last post I did use the correct term of share.
To be clear, Facebook states and I quote --
"When you download or use such third-party services, they can access your public profile, which includes your user name or user id, your age range, country/language, your list of friends..."
Apple explicitly states that they will share PII as needed to enable services, such as when you buy a phone, it will share needed information with the carrier to establish the account or when you are financing, it will share needed information with the credit company. But nowhere are they sharing my age of my list of friends.
Bottom line, I have no issue with a Developer getting statistical information that helps them, and as I stated, they should work with Apple to figure that out. What I am against is sharing of PII. If the vendor needs that, they should ask for it directly, which they certainly are able to do. For example when swift keyboard came out I downloaded it, the vendor asked for root access to anything on my phone (they claim they needed to provide the keyboard service), but I was not comfortable giving them that kind of access and deleted the app. Many are comfortable and use the app without issue. Many games like CoC require you to login using Facebook or Game Center. Again the user can decide at that point. If they agree, then they are tracked by the vendor without any issue. This Spotify claim is not real because as I have shown there are clear ways to get the information. They either don't want people to know or they are too lazy to develop what others already have.
I have information on over 100 million people in my database (including some VERY personal information), and all of it was obtained by front door tactics (everyone was informed and explicitly consented/opted-in). Spotify is not restricted by the app store from getting that if they really want and if people really want to give up the information. For subscribers, Spotify should already have everything they need to track them within their servers. My guess is this is more about non-subscribers.
To your wife's request, there is the old saying - happy wife, happy life. Can't really comment beyond but good luck on the date (if you capitulate)