Tough question. For some things, I'd say that informed consent is hard to give - if you consent, you're not informed.
I don't believe that the average user is making informed choices. The choices may be rational as long as the users don't understand the consequences. It's perfectly rational to trade in your life savings for a fancy meal if you don't understand what "life savings" means.
I wonder how much information can be provided, much of the "giving your data" is really about the side effects and possible consequences....
But you can only tell people so much. Just saying "hey you're giving google your location" (just a generic example here) ... honestly if that's all I know ... so what?
But really the larger issues are other implications.
Exactly, and I think we're usually way off intuitively.
For example when considering how many facts of what nature I'd need to individually identify you. SSN? Ok, done, everybody knows that. But how far do I get with birth date, height and city? What if I add one chronic health issue, no matter how small? Chronic sinusitis, born on August 8th, lives in $city and is 186cm? In most cases, I probably don't even need all four.
But most people intuitively don't think about it in combination, they figure "oh so you know I live in $city, big deal, so do a million other people", "oh so you know my birthday, well a million other people in the country have that birthday".
I don't believe that the average user is making informed choices. The choices may be rational as long as the users don't understand the consequences. It's perfectly rational to trade in your life savings for a fancy meal if you don't understand what "life savings" means.