yes there seems to be a lot more areas more "disadvantaged" doesn't there.
I think you'll find the scale is about disadvantage. it's used by governments to help redress and prioritise services.

I think you''l find Blacktown is one of the largest localities in Australia by population much larger than those inner city areas you cherry picked.
I think you'll find I never said it was the most advantaged area in NSW.
Lots of other areas below Blacktown there mel.
Oh and I think you'll find Blacktown sits around about the middle of the list... not the best but not the worst, much more lower socio economic areas according to you then, below eh... not that your list is actually a measure of that.
Blacktown (C) 968.5
Muswellbrook (A) 968.2
Corowa Shire (A) 967.8
Holroyd (C) 965.6
Boorowa (A) 963.8
Griffith (C) 963.7
Gundagai (A) 961.6
Mid Western Regional (A) 961.5
Tamworth Regional (A) 959.9
Tweed (A) 958.5
Coffs Harbour (C) 958.4
Wentworth (A) 957.4
Cobar (A) 956.7
Eurobodalla (A) 955.8
Temora (A) 955.6
Shoalhaven (C) 954.6
Leeton (A) 954.5
Tumbarumba (A) 954.3
Berrigan (A) 954.1
Narrabri (A) 953.4
Lismore (C) 952.7
Bombala (A) 952.5
Wyong (A) 951.7
Goulburn Mulwaree (A) 951.4
Tumut Shire (A) 951.3
Gloucester (A) 951.0
Liverpool (C) 951.0
Bellingen (A) 950.1
Young (A) 947.3
Forbes (A) 946.8
Gunnedah (A) 946.7
Balranald (A) 946.2
Bogan (A) 946.1
Weddin (A) 945.0
Campbelltown (C) 944.8
Parkes (A) 943.5
Harden (A) 941.9
Junee (A) 941.7
Deniliquin (A) 941.6
Cootamundra (A) 941.5
Warren (A) 941.2
Gwydir (A) 939.9
Lachlan (A) 938.1
Urana (A) 937.1
Cessnock (C) 936.4
Bourke (A) 932.6
Great Lakes (A) 932.3
Bankstown (C) 931.7
Guyra (A) 931.0
Murrumbidgee (A) 928.3
Cowra (A) 928.0
Hay (A) 927.0
Narromine (A) 926.6
Narrandera (A) 925.2
Lithgow (C) 924.2
Canterbury (C) 922.0
Glen Innes Severn (A) 921.8
Inverell (A) 921.4
Liverpool Plains (A) 921.3
Clarence Valley (A) 919.4
Auburn (C) 916.7
Tenterfield (A) 915.4
Moree Plains (A) 915.1
Greater Taree (C) 913.7
Warrumbungle Shire (A) 911.3
Gilgandra (A) 910.6
Kyogle (A) 907.1
Nambucca (A) 900.0
Broken Hill (C) 899.6
Richmond Valley (A) 899.5
Wellington (A) 893.2
Kempsey (A) 879.7
Coonamble (A) 879.6
Walgett (A) 856.2
Fairfield (C) 854.0
Central Darling (A) 824.4
Brewarrina (A)