Credit card, debt card, mobile phone, or an E-mail account if you have them they know who you are, where you live what you buy and where you buy it. From there they know what schools you went to, where you work, what you drive if you have a car, and the sum total of money you have.
Don't you personally think that this is just a little bit risky? People don't even know where their personel data is stored and who has access to it, and wether those that do have access to sensitive data like credit card and bank details, are responsible persons. There were several scandals recently in Germany where Post (mail) employees sold private data to add firms, or that insurance companies employees sell sensitive data onwards to whomever is interested. I don't really want my information accessible by jus about anybody.. and I don't have a credit card, and I certainly find it creepy that the US Government could find me via my gps passport lol.. Orwell says hello.
I once asked a border control guy in Newark if anybody ever answered those questions with yes when I was visiting NYC about 10 years ago - honestly, those questions are ridiculous! If I were a terrorist or someone with nefarious plans, I would certainly not announce it in a form like that, or admit that I commited genocide and am in fact a war criminal. I doubt that you catch anybody through that questionaire.. or those bozos that you do aren't really very clever.
Even so, my name is probably stored in some database already because I once tried to enter the US without a visa.. even though that wasn't my fault. Friends of ours had chartered a plane and invited us to fly back to the US with them, and we didn't really know that we needed a visa when traveling on a private carrier. It was quite the experience lol.. nothing happened, we had to pay 200 dollars each to apply for the waiver, and the pilots had to pay a huge fine for bringing someone inside the country without a visa. There was nothing criminal about it, but the border control lady was pretty tough. She initially told us we could either go back where we came from (Shannon in Ireland) or go to Canada and apply for a visa or we could do it right there but then we had no guarantee that we would get it, and we would have to pay the 200 bucks wether we got it or not. I'll never forget it, they opened up and lit a checkin hall just for us.. it was huge and empty except for us. it was quite the experience. Thankfully this didn't hinder another visit to the US a few years later with a regular commercial flight.