You can have a non-life threatening injury that prevents you from operating a car yourself, and without access to something like Uber or having another person to drive you, could necessitate calling an ambulance.

A study was done (I haven't read the whole thing) that seemed to indicate cities with UberX had a reduction in ambulance use: http://www2.ku.edu/~kuwpaper/2017Papers/201708.pdf

(Though the wording of the GP was slightly ambiguous and seemed to compare a time-sensitive emergency to being able to take some other vehicle to the hospital)