Yes "monkey44" that is true, but there are some Jetpacks shipped that have failed. Verizon uses the "data usage" taking place at the unit, which can be quite a bit more than shown getting to your computer.
I would think a customer could use the total amount of data used at the computer (if they have an APP set up to track it).
But; here's the rub. They will most likely claim you have other devices also connected through "Wifi" also using the internet to make it harder for you to argue about the amount of data used.
You are kind of stuck between a rock and a hard place when this happens.