The state has an incentive to encourage callers to wait for trained emergency drivers. Nobody wants mom in a panic and flying through red lights at the intersections.
Or worse, my former teacher drove himself to the ER while in the midst of a heart attack rather than wait for an ambulance. He didn't survive the attack but made it to the hospital without incident.
edit, to add this old gem: "I want to die peacefully in my sleep, like my grandfather. Not screaming and yelling like the passengers in his car."