take for instance... the fentanyl is a transdermal SR medication... but a PCA is usually 50mL of straight Fentanyl, Dilaudid, or other medications. Thats 1mg/mL x50 mL's. Can you imagine the potential lawsuits and legal actions happen if a Basic decides that he wants to take that PCA? Perhaps he/she manages to get a hold of the PCA Pump Key (which isn't that hard to do) and while the PT is... let say asleep for a long transport... decides to swap the 60mL syringe with 60mL of NS or SW?
I'd be more worried about a paramedic doing that than a basic.. I don't know about there, but here basics on IFT trucks don't carry saline and syringes to do the switch.