I'm in the U.S. How fast an ambulance will get to you here really depends on how functional your local infrastructure is, and that depends largely on the wealth of the local tax base. I used to live in Detroit, across the street from a hospital. Detroit is very poor. One time a guy got hit by a car in front of my apartment building. I didn't see the accident, the dude was already lying in the street when I came home. I called 911, and the operator was like, "Yeah, we know already. Quit jamming our phone lines." So I went out again and did errands for maybe 45 minutes. When I came home, this poor sonofabitch was still lying in the street, LITERALLY 100 FEET FROM THE GODDAMN HOSPITAL. An ambulance had finally arrived and they were just putting an oxygen mask on this guy. His skin had turned gray. I was like, "WTF kind of dystopian satire is this?!"
I now live in a suburb in a pretty wealthy area, about 5 miles from the nearest hospital. I've never had to call an ambulance for a real life-or-death emergency, but the one time I injured myself badly enough to need transport to the hospital the ambulance was here within about 15 minutes. I'm sure if somebody's baby wasn't breathing or something, a first responder of some kind could be here in 5 minutes or less. (Normally when you call 911, every possible vehicle with a siren on it shows up: cops, ambulances, fire trucks.)
It's also worth pointing out that southeastern Michigan is ridiculously segregated—Detroit is about 80% black & its suburbs are about 80% white. The same social forces that caused this demographic contribute to Detroit's horrible infrastructure and general lack of services of any kind. Naturally, the poor bastard who (almost?) died in front of the hospital was black.
So just how fast an ambulance will get to you depends a lot on the city you're in, and the wealth and racial makeup of that city's residents. "All men are created equal," bald eagle with an American flag in its beak and a tear running down from one eye, etc., etc. <—(assorted U.S. symbols if you're not familiar.)