When you say, data usage is dependent on the phone, you're correct but there's a downside to using those kinds of devices. They can be very sluggish.
And like I mentioned in my post on this topic, it could be that so many automatic updates are running in the background of the phone that's why it uses so much data.

I used to suffer these data issues until I made adjustments on my phone. Maybe you should refer to that post and try out the tips I have. You may find them helpful.