Regarding the license plates, looking up, privacy, etc.--- Demmi makes a realistic point.
A ton of info about you is "out there", but usually in little pieces scattered about. Are you comfortable posting on a forum with an amalgam of your personal info...full name, address, phone numbers, email addys, license plate numbers....(it has nothing to do with having something to hide). It has to do with people knowing more about you than you would like because they can choose to misuse it. Anonymity is the first line of defense...getting lost in the crowd, not attracting the most attention so to speak. I can pick a social security number, but it's not a lot of use until I can add a name, address, etc. You may tell people you have migraines, but you may not want a potential employer to know, they may not hire you because they think you won't be a good employee. Plus there are a lot of nutty peeps out there...you can avoid them usually when you're out and about, but what about the nut job sitting at the computer all day all night fixated on you for some reason? It happens.
I have a pet stalker out there. I believe she has people she knows trying to connect with me on Linkedin so she can get access to my other connections. Why? So she can know more about where I am, what I'm doing, where I'm working, who I know so she can contact them. It's not fair that I should have to be so cautious, but it's an eye opener as well.