Why not regulate PPPs?

Regulation of public utilities and infrastructure is being generalized worldwide. However, when there are public-private partnership arrangements, it is assumed that the contract signed by the parties is adequate to protect the public interest, and therefore, external regulation is not necessary. Even though explicit regulation also has its shortcomings, we disagree with the preconceived idea that contracts alone always protect the public interest. Contracts avoid the discretion left to regulators, but they are imperfect and incomplete. Therefore, we defend the need for regulation and posit that it should be combined with a contract, resulting in a game of positive sum.