In Czechia we have sufficient capacity of ambulances and other emergency services. What happens is that off peak they serve to help move old people to hospital, like a super expensive taxi. In these cases I can see how "emergency Uber" could help. On the other hand the doctors serving in these ambulances are usually extremely well prepared, the best MD students go to study to serve there. Even if it is one in a hundred cases, they will recognize the stroke from a random chest pain. Replacing them would surely increase the death rate in these cases...