What is the test for an improper exercise of government discretion in the context of sidewalk inspections?

The plaintiff submits that the defendant's "policy" of having no schedule of inspections of sidewalks and roads before June 1994 is "so irrational and unreasonable as to constitute an improper exercise of government discretion", as that test is enunciated in Brown v. British Columbia (1994) 1994 CanLII 121 (SCC), 112 D.L.R. (4th) 1 (S.C.C.) at p. 11, per Mr. Justice Cory. That decision establishes that the person who asserts such an improper exercise of discretion must prove it on a balance of probabilities. Here, the only evidence offered is the fact that there were no scheduled inspections. From this, an inference of irrationality or unreasonableness is invited. But, as submitted by the City, it is not unreasonable not to inspect if a bona fide policy decision has been made that certain hazards fall below a threshold established due to budgetary or manpower considerations. That is the evidence before me.