Could this go on to contribute to the explanation of the increase in expansion of the universe? if the distance between gravitational wells is increasing then the gravitational effect on the electron / positron pair would be reduced prior to them recombining in to a photon?

Funding modelling is never a straight 1 to 1 scenario as put forward here. Local Government is able to redirect funding from health, as a result of fewer speed (and alcohol?) related accidents. Plus fewer dead / disabled people of driving age generally means more taxation dollars flowing back in to the economy. This can all be redistributed to allow for funding of local law enforcement as required.