We ran an import business that distributed Australia-wide. Also ran a local office. Same retail prices to everyone. No issues. Didn't upset customers, didn't upset distributors.
By Spotify offering two pricing levels, they look foolish and treat their customers with contempt. Apple is also their customer being a distributor of their products. For that, they deserve to make money. Without the Apple iOS platform, Spotify would have less customers.
To email customers of Apple directly is underhanded. There is ONE player in this game that isn't playing by the rules.
Apple would be right to boot Spotify from the App store. No distributor would put up with a supplier acting like this!
Longterm, there will be one loser. It won't be Apple.