What else is the medic going to do? every call, regardless of nature, gets an response of an ALS capable ambulance. if the call is ALS the medics rides in the back. if it's BLS, the EMT does. if it starts BLS and goes ALS, the crew can switch positions. As for the rationale for having an all ALS ambulance system vs a tiered system, that was waaaaay above my pay grade.