If the damages were $2 and not $200,000 would you still think an 18 month sentence is justified ?
I would guess that most people would think not.
So the true cost of the damage is a significant factor in assessing the appropriate punishment
From what I can tell, virtually every crime against property has a process for settling damages irrespective of the amount of time served in prison. "10-15 months in jail AND a fine not to exceed $50,000", and so on.
That might not be the right way to do it, but it's the way it's currently done, anyway, which means that courts have to inquire into the "true" damages sustained in order to determine what crime the person should be charged with.
A solution could be not to take damages into account in cases like this, so the crime would just be "stealing a meter's SIM card and using it", which would be the same crime regardless of how much money that cost the utility.
I would tend to disagree with this. Having to repay damages removes the benefit associated with the crime, so for ordinary sane people, it would act as a deterrent. In my opinion, jail is more appropriate for crimes where the criminal is likely to be an ongoing danger to society and no other option (probation, mandatory classes, etc.) would have the desired effect.