Wait! Let me get this straight. If you own a 250 gram toy drone you need to register it because it could be dangerous?
But if you own an assault rifle with 100 round magazine you don't need to register it. Yes, only in America.
No all legal assault rifles owned by civilians are registered in the US and require a in depth background check by the FBI and a tax stamp, gun dealer licence, and large transfer fees. Assault rifles are full automatic (pull trigger bullets fly until you let go), what are unregistered is semi-automatic (one pull one bullet) and manual (pump action, lever action, etc), semi-automatic and manual require a background check and often a waiting period, unless you have a concealed carry permit in that state or dealer licence (in which cases you have already passed the background checks). The only firearms that do not require a background check at some stage are black powder firearms in most states.
Additionally we have a constitutional provision protecting right to own firearms. But we have no such constitutional protection for ownership of RC toys.