False positives cost more than just money. There are a finite number of ambulances in any given area. We try to staff to cover the false positives we know we're going to get, but there's just no way to predict when we'll get hit out for a stubbed toe and someone with a head cold they've had for the past three days and someone who forgot to refill their prescription for their cholesterol medication and an intermittent ringing in your left ear (I'm not making these up folks... these are just a sampling of the BS calls I've been on in the past week or two).

So while crews are off dealing with those non-emergencies, they are unavailable to respond to things like cardiac arrests and strokes...