Osx has, for a little while now, had a "metered" flag for networks. Not sure which apps, if any, respect it, but it's there
Yes, I mentioned that in the post you responded to.
> Not sure which apps, if any, respect it, but it's there
It reduces data consumption for me about 1/5. Not nothing, but the Mac can easily consume hundreds of GB of data a week doing "normal" activities. YouTube on a MacBook is many times more data than the equivalent on a phone screen.