None of these are reasons for ambulances to not be autonomous. If you accept that most other vehicles will be fully autonomous, ambulances do not require anything further extraordinary to also be autonomous. The vehicles on the road would likely be networked, at least within a nexus of proximity, and move out of the way of the ambulance so it could speed past them.
NB: I’m not saying ambulances will be autonomous. I’m just saying that if everything else is, the ambulances have no significant (technical) obstacle for also being autonomous either. A significant theoretical advantage of fully autonomous vehicles is not simply that the modal vehicle is safer than a human, but that a networked and autonomous fleet is hyper-efficient and hyper-aware as a hive mind.