This is not my field, but I'm trying to understand crypto-currency econ here so please clue me in:

So if the only reason for mining in currency blockchains is the incentive to earn, what would be the incentive for a private blockchain network that didn't incorporate a currency? Could it be that their incentive is the reduced cost (in fiat money) of doing business? So that they could in effect voluntarily do the verification part of mining without the need for currency incentives?

I would imagine that it shouldn't be too difficult to set up enough adversarial but voluntary mining parties in a huge financial system such as the US financial system to bring a collective sense of safety to that closed blockchain no?