It’s because it counts as an aircraft. Getting licenced to use your drone for anything more than “wooo, flyin mah drone” covers a lot of the same stuff a private pilot would know like reading the maps, airport landing procedure, and airspace. They treat it like an actual airplane. And you can’t just start blasting at airplanes because they flew over your house. If it’s doing more than just flying over it has to be addressed legally.
Hank Green can tell you the full mystery:
https://youtu.be/acEIGorImGs?si=_xi2IF-GEssAuyZ-
tl:dw: We knew that’s where baby eels came from but we didn’t know how the adults got there or what the larvae looked like. Baby eel larvae was misidentified as another species and adult eel can take up to 18 months traveling at the bottom of the ocean to get there, during which time they grow their gonads which was another mystery.