This is the Wiki
This is what it says:
How do I find a abandoned Mainland parcel to purchase?
Recycled land is owned by Governor Linden and named, “Abandoned Land - For Sale.” These parcels can be found my visiting a region and looking at parcel descriptions. They will also highlight on the map as land for sale. These parcels are not listed in Search.
(emphasis is mine)
I have specified just a couple of parcels of an increasing number that are listed in search
& thus accessible to bot's data filtering.
Sadly, at this stage , the policy, which in my opinion is a good one, is definitely being poorly implemented.
IF official wiki & actual practice do not concur, it can not be called good implementation