Does a hard-wired EV charger (EVSE) need an isolator for the supply wiring?

In a word, NO. Not technically.

Consulting the good book AS3000 there isn't much on EV charging and what there is goes to New Zealand only. However, page 224 shows that over the ditch EVSE are considered a socket outlet, not an appliance or device, see clause 4.4.1.3,

Then look at page 226, clause 4.4.4 where it explains socket outlets shall have a switching device. (need not be an isolator) You could apply Exception 3 to the clause to meet the requirement, i.e. a socket outlet switched by the insertion or withdrawal of a plug is deemed to comply.

However, you can, of course, exceed the standards and install one. Maybe even use a conventional socket outlet so the car charger isn't hard-wired. Makes it easy to service, repair or take to your holiday house.