ikr , Korean war was like 40 years ago, 9/11 like 20. seriously thought the draft was a meme and had no idea its still a thing and actually illegal to not sign up. you'd think they'd send you more than 1 letter when your 18. also you'd think our schools would tell us about it.
You must've manually signed up yourself. Maybe you got your letter or maybe you needed financial aid and had to sign. However if you didn't know about and just got your license, Cali is one of like 5 states that don't force you to sign up.