Because they can make something without a serial number an NFA item...
I can't wait for this scare to die down. I have trade offers right now where people are trying to tell me a WASR 10 goes for $1000. Luckily I'm perfectly happy with my Mak 90. I've told people that want to trade me their AR for what I have that I won't pay stupid prices and they've walked away. I'm not raising my prices on what I want to sell. Everyone please join me.