Attribution is required, however that does not stop them applying any other license they want. In other words, the maps they create are not CC-by-SA - they are

Attribution is required, however that does not stop them applying any other license they want. In other words, the maps they create are not CC-by-SA - they are "Produced Works" and can be All Rights Reserved if the publishers want. (although the map data would still be copyright OSM contributors)