And all subject to high rates of false positives. Also see OFAC, where a simple first/last name match makes it impossible to bank in the US: https://www.treasury.gov/resource-center/sanctions/SDN-List/...
I was taken into a side room by 2 plain-clothes policemen, who politely asked my several questions about why I came to Australia. At the end of it all, they apologised and explained that my name matched one on a watch list, but my age, hair colour, build etc didn't match - "but it's procedure". They also said it would happen every time I went to Australia (I never did go back tho).
It seemed incredible to me that they would use only a matching name as their reason to be suspicious of someone!
As I said though, they were very polite about it, and I never felt like I was under any kind of threat or danger, and they didn't invade my privacy (they didn't look at my devices, and didn't even search my bags). A stark contrast to my experiences at US border control, I must say...
They Check the box, then the screen agent takes a closer look, "Hmm, this nine year old indian girl named Charles Manson is probably not the 70+ year old dead man that we were worried about"
If you sign up with name, birthdate, and address, maybe the system comes up with an 85% likelihood that you're that Manson. But if you check the box, you can add in data like place of birth and SSN which prove you aren't the infamous murderer, so the system (or more realistically, a human with override powers) can clear you. That's way better than being silently blacklisted, or having each interaction delayed until it can be separately verified.
Presumably, Manson wouldn't want to check that box because he'd be likely to get arrested, and if he did then the subsequent data would all just confirm there's a problem. It's not a great system, but it's a decent improvement on just making a decision without the extra caution.