You don't even understand that it's not the "personal experience of one single journalist he had in one city". "Speaking from the city of Mainz" means he is tal

You don't even understand that it's not the "personal experience of one single journalist he had in one city". "Speaking from the city of Mainz" means he is talking from the ZDF headquarters, that's all. Obviously it's the feedback the TV station got from all over Germany.