Or when I get an email, whatsapp, my device is sending location data, waiting for a command, doing updates and all those other little pings and data transfers that happen 24/7
Your view is dated.
No, my view is spot on! It is not dated. It is the basis on how all this works. Why do you think I put in the words "Data is transmitted when required to do so"?
YOU have chosen to allow those Apps to do the background stuff and set them to send "acknowledgment of receipts, whatsapp reports back to the network, doing back ground updates, little pings and all that stuff". They only do that when required at which stage they fill a packet and send it through the port. The port is "open" so that they can do so at any time because you have an always ON service, no need to dialup first. All 24/7 means is the gate to your system is OPEN, nothing more.
IF you fully control data flows OUT of your system, then, you CLOSE the gate and ALL apps have to wait for you to OPEN the gate.
And BTW in our country we pay for data SMSs and CALLS made, NOT for data received ( hopefully it is still like that for data etc, it is still the case for voice calls). On the receive side, IF you put in security, the Port is CLOSED and when a packet arrives some negotiation takes place before the packet of data is allowed through, The Gate is Opened and then Closed again.
The data you transmit is accumulated and counts off against your package, INCLUDING all this background stuff.
That is why ALL the operators will first respond to complaints about "dissapperaing data" by saying that you have set up your phone, whatever in such a way that you are unaware of all the background data flows going on. IF you choose to leave everything at defaults then sure BUT IF you take the trouble to see what is going on you will CLOSE the gate for this stuff, and regardless of the "always on" or "24/7" status, NO data flows when the gate is closed.
ALL my devices are set like that. The gate is CLOSED, just like the gate across my driveway. NOTHING enters my system that I am not aware of. OF course this limits me BUT it means I am in control of MY stuff. IF I choose to allow Whatsapp to communicate in the background, keeping me update to date and the "network" up to date about my Whastapp status, then it is because I have decided to allow this, not because Whastapp has or wants it.
This concept IS at the heart of truly understanding how things work in this environment. And it is simple when you boil it down to the absolute basics.