First, Cops DO pull over cars even if they have EMT or VAS plates.
Regarding lights and sirens, I do not believe that Hatzoloh members abuse them, the consequences are to big to use them when not on an emergency.
You might see someone turn on the lights and sirens only to shut them a few seconds later, this happens all the time, either the patient stopped choking or the first member on scene radioed the units to slow it down.
This happens almost each day. There are those people who are out to correct the world and make sure to call the dispatcher on the hotline that unit so and so used lights and sirens to go through a red light.