You can not always blame the buyers.....I have had the same address with the same postcode for 42 years.  The local post office is in the same postcode too...just round the corner and down the street.

But because there are also 4 other surrounding suburbs with the same postcode I get told by sellers (often very rudely) that I have to change my address as it can not possibly be correct.  It is correct, and I can not change it.