PAs are able to prescribe medicine as they have had training in general medicine and have a need for it. AAs do not really have a need in our OR role. In reality, more training is needed if AAs wish to prescribe medication and this will encroach on AAs being PAs. I don't think PAs would like this and there really is no need at this point.
The only setting where an anesthetist would be doing outpatient prescriptions would be in pain management - which is something PAs already do and CRNAs are fighting for the right to move in to all the time. Probably not the best of battles at this point of our existance.