Some of it is the high taxes of course, but also higher wages. For Norway in particular their agriculture is extremely limited so they have to import a lot of food, in order to protect what production they do have, there are sky high import duties on most things. And being on the edge of the continent it's not realistic to import everything from places like Spain or Italy with lower production costs, but have to get it from Netherlands, Germany and Denmark which have higher costs, but can provide fresh vegetables.