The entire medical system needs a rework, in my opinion, but I don't think civs should ever have the power to revive people to the same standard as the NHS. It should also be difficult to do: defibs, IRL, are expensive bits of kit!
From a gameplay point of view, I can see the benefit of having civs be able to treat other civs when there are no NHS on duty, however I think that there should be massive limitations on this. For example, if a civ revives a civ then they should have next to no health and need to visit the hospital ASAP - possibly even falling unconscious at random intervals to simulate severe trauma. There should then be a "check in" NPC at Pillbox that, when interacted with, will teleport the patient to an empty bed where they have to spend the next approx. 2-3 minutes getting treated (healed) before being allowed to leave. This adds consequences to actions, and improves the realism.