Yes, the use of objective values that don't correspond with market values has always been an issue between Greece and the EU and one of the bail-out conditions was to bring them into alignment. The problem is that the Greek property market is so disparate it has always been difficult to decide what the market value should be. For example look at the third paragraph down, i.e. they are already expecting surveyors to provide widely different prices in some cases.
Even now they are not aiming at real market values for each house. Their aim is to assign for each area a typical value per sqm for properties in that area, i.e. a zone rate. Clearly the actual price of houses in Kamisiana, for example, are not the same as in Kiffisia so Kamisiana and Kiffisia will have different zone rates. The method of calculating a value will then be the same, i.e. multiply the zone rate by the property area and then tweak a few things. In reality would two 150 sqm houses in Kiffisias automatically fetch the same price?