Spotify is known for its shady tricks. Try figuring out that the client consumes a very large portion of your upload bandwidth. Another one is when they enabled the "local files" feature via auto update a few years ago, this feature not only allowed you to play mp3 files via the client but also phoned home to mama with a list of all your local music. There was no way to opt out of this, the client just auto updated and started importing everything from windows default music directory. It seems as though they update their TOS every time i restart the client also, who would read that when you are in a rush to start your music.
The way they remove songs from the library is also a bit disturbing, some songs become gray and some just silently disappear. The frequency of removed songs is also quite high, for a free service i don't mind but if i pay premium and tons of my favorite songs disapear for each day i'm not going to be happy.
When they introduced the option to play local music, it was a pretty big launch and you were notified. And it has always been easy to select where to grab local files from, or disable it. I think your point here is invalid.
The fact that they remove songs is not unethical, so not really relevant.
The way they remove songs from the library is also a bit disturbing, some songs become gray and some just silently disappear. The frequency of removed songs is also quite high, for a free service i don't mind but if i pay premium and tons of my favorite songs disapear for each day i'm not going to be happy.