Preheat oven to 350 degrees F (175 degrees C). Grease a baking dish.
Mix ground beef with onion powder, garlic powder, salt, and black pepper in a bowl; form mixture into a loaf and place into prepared baking dish.
Bring root beer, raisins, Worcestershire sauce, and ketchup to a boil in a saucepan; reduce heat and simmer until flavors have blended and raisins are plump, about 5 minutes. Pour raisin sauce over meat loaf.
Bake in the preheated oven until meat loaf is no longer pink inside and an instant-read meat thermometer inserted into the center of the loaf reads at least 160 degrees F (70 degrees C), 25 to 30 minutes.