It's easy to stereotype places, especially if you have never been to them. After all, you can't remember everything about every place that you know of in the world. It's easier to just give them one or two things that they are famous for and go with that. In this map, you can see the main things that these countries are known for, at leat in the eyes of the Japanese.
Some of them are pretty obvious like Italy and the mafia, but why is Hungary known or lard and Latvia as a place that cannot eat potatoes? Where did they get some of these ideas?