I know of 2 incidents within the last 18 months at ONE airport where the presence of an on-site ARFF meant that an incident never developed to the point of the authorities being formally notified. Their presence meant that no formal report was required. One incident would have, without a doubt, caused the loss of 12 lives, the other prevented 180 lives being put at risk.
But they never made the news or the reports because the on-site ARFF crews prevented it from developing. Had they had to wait for municipal crews lives would definitely have been lost in one incident and could have been lost in the second.