JM: I think the all the red tape is because I am mainly referring to native mammals, more specifically nocturnal mammals (possums, gliders) that have highly specialised nesting/feeding requirements, etc. And you can't have a licence to have these as pets in the first place (unless you own a zoo)! I think thats why NPWS are extremely careful about it.
I haven't yet heard about anyone in Wires keeping a reptile on as PC (permanent care), if they overcome their injuries they are usually releasable as they can adapt to their injuries better than mammals. If we get an exotic in (and believe me, we get many), then we notify NPWS immediately and it is either taken to a zoo or put to sleep. We get a lot of escaped illegal corn snakes apparently although I'm yet to rescue one.