This is hugely true...In Greece, law has changed, so that you have to carry them all the time, from November to march, and have to place them, every time there is a police announcement, for a specific region...but that's on papers...in real, you have to place them, mostly in touristic or crowded region where controls are constant...it has happened to me, a couple of times, travelling to south Greece, in Peloponnese territory, where the police stopped me, before entering a snowy part of the road...they asked me if I have chains, I answered that I have snow socks with me plus 4wd, they gave a glance at the car, and let me go, advising, to put the socks, if I face troubles...snow was about 3cm, for about 20 Kms....I passed with speed around 60 Kms/h, no problem....it has happened also, during a trip to central Greece with heavy snowfall, motorway covered up to 3-5 cms with snow, I passed normally with speeds up to 90 Kms/h, no problem for me, no stop for control by anyone....in northern Greece though, close to Fyrom or Bulgarian borders, controls are more often, but anyway, drivers there, use winter tires...most of them...