[Y_Y]

You don't have to be that healthy to call an ambulance! As long as not everyone in the sick-and-poor commune has a heart attack at the same time this should be a safe enough system.

[e_y_]

Ambulances are expensive enough that people are hesitant to call them, sometimes even in life threatening situations.

And if the person is unsure whether the situation is critical, they might try to "sleep it off" rather than driving or getting a ride, because ER is also kind of expensive and you could be stuck there all day.

[Qem]

In US. But there are places with proper socialized health systems, where one must not be afraid of bankruptcy by calling an ambulance.