How can Fraggles be naive about human technology or conventions and then mention them in song?
LOL, that has always driven me bonkers. How do they know what a lawn is? How do they know what a TIGER is? You just have to let it slide.
There should have been SOMETHING about parents. They never mention or imply them, not once. I assume the 5 are supposed to be in their late teens or early 20s (according to the Fraggle lifespan), but their parents never call on them or send them letters or anything. Save for maybe a scene or two, you don't really see parents or babies at all. Uncle Matt, the Storyteller and World's Oldest Fraggle seem to be the only adults around.