Specifically with smartphones- the built in controls to keep you from blowing through your cellular data plan don't apply when your wifi...is connected to a meted plan. So your device thinks "I'm on wi-fi, update all the things" yet the connection still "cellular".
It would be a sad day in tech when your device OS has to implement an "airplane-esq" mode for metered connections that drops all data-intensive usage and maybe only allows certain notifications through.
> Network bandwidth management: New API provides ability to detect metered networks, including tethering to a mobile hotspot.
Mark the WiFi access points you want to be low data usage and you are good to go. Software that plays nice will use the "isActiveNetworkMetered()" to check if they should download or not.