I understand why you say this, and I used to think that way myself and it makes rational sense when you compare the way government runs when you look at how you

I understand why you say this, and I used to think that way myself and it makes rational sense when you compare the way government runs when you look at how you most probably work in an efficient team, getting things done etc (or maybe not!) . But.. This seems too simplistic a rule to apply to large and complicated projects which likely are the case with creating and maintaining infrastructure. If private investment can't calculate expected return they don't do it and this often is the case with complicated projects there is often high risk involved and no easily attainable reward (from a financial perspective). This is why public / government undertakes these projects because they know what the expected benefit is to society and are not driven by ROI in the same way as private enterprise. Your model needs to take this into account in order to be more persuasive.