Currently both ghouls and mechs are just shown as friendlies on the map. At times, such as when you have other friendlies on the map, this can make it hard to quickly determine where they are located during raids or other events. If they had a separate category then they would be much easier to see on the map. Basically splitting them off from friendlies in the same way that tamed animals vs wild animals are very similar but noticeably different.