Today's example of a P3 is one announced recently to build out the airport in Anchorage, AK.
The objective is to increase economic activity, which will provide more jobs and revenue, meaning more tax and fee income to finance government services. Basically, wins all around.
"Compared to other west coast gateways, ANC has significantly lower operational costs and is not congested. ANC’s international terminal presents a tremendous opportunity to capture future passenger growth. Governor Dunleavy’s message is that Alaska is open for business and the airport is looking at partnering with the private sector to drive growth at ANC.”