In 1954 there were 15000 cars in Greece. By 1985 there were 1250000, or 83 times more!
Athens doesn't have enough space for all the cars. The previous GBR of '73 allowed the pilotis, or the building of multiresidences on pillars to allow for ground floor parking, but this wasn't enough for the constructors to embrace it. Very few multiresidences actually did have pilotis before 1985.