Than What is the meaning of "used"?

I mean, it wasn't clear to me without the explanation (I too thought it used 1TB of public internet data), but it's clear now that it is accurate (it literally used 1 TB of private network data)

It might not seem to be anything (people will assume private network traffic is free) but there is a cost - it's capacity that could be used for other purposes, eg. home alarms.