I also get this as US Citizen and there is nothing stopping you from entering the US except your patience. You could refuse to answer and then be detained for further interrogation. but eventually they'll have to let you go. Most people, myself included, have an event to attend or plane to catch so we answer to get it over with, quickly.
One time I was going to a wedding and I didn't know where it was because my family sent a cab to take me to the hotel. Border guard told me to go to the payphone (hadn't used one in years) and get the address. I complied then asked her what was preventing me from walking out the airport. She told me absolutely nothing. Although I imagine some information would probably be enterred in the USCIS database.
If this is indeed the case (I heard otherwise, scary stories about the legal immigration gray area, but don't have the time to hunt down relevant URLs at the moment), then why do people put up with this sort of harrassment?
I mean, the land of the free, and all that — and border guards tell you to go to a payphone to get the address of the place you're going to? This just doesn't make sense.
Like I said, timing. Most citizens clearing immigration know they have a legal right to return. They don't know how long CBP can detain them. I think the rules say a "reasonable amount of time" without actually assigning a hard value.
One time I was going to a wedding and I didn't know where it was because my family sent a cab to take me to the hotel. Border guard told me to go to the payphone (hadn't used one in years) and get the address. I complied then asked her what was preventing me from walking out the airport. She told me absolutely nothing. Although I imagine some information would probably be enterred in the USCIS database.