There are two others that I would know. They're sort of in the sphere of risk, or at least one is.
One is contractual interface risk. In the normal process you would issue a contract for somebody to design it. Then you would take that design and you would issue another contract to build it. Who takes the contractual interface risk between the design contract and the build contract? It is the government. If the design is wrong, and something happens with the build, they both point at you. Package them together, and you reduce risk because you're not taking the contractual interface risk.
The thing that people miss most is the innovation potential that you get. I mentioned that a bit, but in a P3 you can tell them what you want them to achieve, for example, to carry passengers from downtown Vancouver out to the airport, or to build a road from here to there.
I've been in the public sector a long time. The public sector is really great. Its core mandate, in my view, is to figure out what citizens need and how to pay for it, but leave it to the people who are the experts to figure out how to deliver it. I have thousands of little anecdotes ranging from the small to the very large that if you give them the freedom to bring their expertise to bear, it's amazing the results you can get. I'd be happy to share some of those anecdotes.
Governments tend to over-specify in their contracts: they want the bolt to be this big, or they want something to be that size. That disables the ability of the private sector to innovate.