Strictly speaking the DNC law does apply to scammers. Its one more law they break.
Many scammers are using spoofed numbers. They are really calling from outside the US, often from 3rd world countries where scamming dumb Americans is not a crime and the local police do not cooperate with police from the US. To punish them we have to catch them, and that's nearly impossible.
Got a call from this number just moments ago and immediately looked up while it's still ringing without answering, I see it's other spam call. Ugh, too many spam calls on the cell phone as of lately. Feds are worthless [***] when it comes to DO NOT CALL registry list!!