Does the contract that CHC signed specify NVG would be used /implemented on the contract?
I suspect not and that is where the problems between a Govt and its contractors start.
At the point where the need for NVG is recognised - presuming the contract was written without it (unforgiveable in modern SAR) - the contractor says 'It's not in the contract - we need more money to provide that additional service level'.
The Govt has allocated a budget for SAR and it has spent it - not wisely it would seem - and can't lose face handing out extra cash to a contractor as that might set a precedent and/or make them look incompetent or foolish.
Round and round it goes until a fatal accident where both sides can now blame the other.
You only get as much safety as you are prepared to pay for........