Yes, this is absolutely true, sorry I did not mention it earlier. There are all sorts of weird stories concerning this legislation.
I was reading in a Greek speaking forum for electronics, that a guy was testing his new radio scanner. Apparently, during testing the scanner got accidentally locked to the frequency of the police, but he claims he didn't notice so, which I have no reason to doubt about. Then he put it in his car and drove back home. On the way he was controlled by the police, which found the scanner, saw the frequency and dragged him to the police department. I am not sure what hapenned in the end, but he was lucky to be a professional on the field of telecommunications.
Another piece of news in local press of Xanthi, recently reported that the police arrested... the manager of a funeral, who was monitoring the frequency of the fire brigade and the police in order to be the first one who will offer his professional services. Crippy. He was always the first one to show up, so it is obvious that they suspected him or he was snitched by one of his competitors.