Does Australia have the 28 day rule, such as exists in the UK? It states (roughly) that you can land/take off from any private land with the landowner's permission for up to 28 days in a calendar year, without having to get planning permission for change of use of that land.
On any one of those 28 days, you can land/take off as many times as you like, with as many different aircraft as you like (hold a mini-airshow), but it still only counts for one of the 28 days.
Probably some people operate from private land in the UK and don't bother to keep accurate records of the number of days/dates when doing so. They just rely on the friendliness of neighbours not to keep a close count of movements, or to report them to the authorities.
After 10 years with proof of operating from your own land without official complaints from neighbours, you can apply to the local authorities for change of use to become an airfield and they can't refuse you. But no doubt they'll charge you increased rates for the privilege.