On Android (and I think iOS, too) you can restrict WIFIs, when they are behind a data plan access, e.g. a 3G/4G internet access. I have this everyday, when travelling by train in Germany. The WIFI access itselve is for free, but limited in bandwith and data usage per guest. Everytime I connect to the WIFI, Spotify starts updating the playlists and downloading the songs.
As I have marked the WIFI on the train as restricted, my Android and as it seems all other apps respect this and just use this WIFI for "normal" internet access, but no mass downloads or system updates. Unforntunately Spotify doesn't respect this.