That contract could have been written to make them contractually liable for $75 trillion dollars. Following your logic, it would then be easy to establish $75 trillion dollars as a basis for damages.
This is not a case about a penalty clause; the damages here emerge straightforwardly from the MNO's usage contract with the utility. The thief didn't stumble across a landmine clause that said "parties agree theft of SIM card incurs $100,000 of damage"; instead, the thief continuously used a metered service that resulted in a 6-figure charge.
One imagines it would be possible to dispute a six-figure liquidated damages claim by arguing that the metered charge was devised in such as way as to deliberately create a penalty clause. My point here being, these things aren't so black and white as to be trivially adjudicated by geeks on a message board. But I think we all in the back of our heads realize that the fee structure for smart meter mobile data isn't an elaborate scam to entrap SIM card thieves.
So, no, your example doesn't work. Companies cannot simply write "you owe me a zillionty squillion dollars if you steal my stuff" and have that hold up in court.
So I do believe that knowing the true damages, and not just the dollar figure specified by the contract, is relevant here.
If you or I accidentally ran up $200K in charges due to somebody stealing our SIM then yes, we could probably negotiate it down. In a big-business-to-big-business context, though, Telstra is as likely as not to say "Hey look, that's what the contract says, you signed it, so suck it".
Without any information to the contrary, I'm willing to believe that if the court decided that the actual damages to the power company were $183,000, then the actual damages were $183,000.
The position you're advocating is that a contract between two private companies should be used to calculate damages for a criminal act. That's a very bad idea - it makes those companies legislators.
If the shopkeeper says the loaf of bread was worth $200K and the the court doesn't question the amount because the shopkeeper has been billed $200K for replacement of said loaf according to a contract with the bakery, the shopkeeper and the bakery have legislated the punishment for the crime.