. There is no possible way that any person humanly possible uses less than 250MB of data on their iPhone unless they don't have an iPhone.

Really? Out of curiosity, are you getting those numbers from your Service Provider? Or from your phone? (I've heard of providers claiming higher amounts than the phones indicate.)

My phone (yes it is an iPhone - 3GS) says that I've sent and recieved 4GB of data ... since Sept 09. That's an average of ~180GB per month (assuming I didn't punt horribly on the math somewhere.)

Granted, that's higher than I expected, but it's well enough below the 250MB per month cap that, if that were my cap, I would still have some room to do more each month (on average.)

Enhanced visual attention is also useful for your everyday person -- such as anyone who drives a car.

what if the black box information was encrypted in such a way that only the car owner could decrypt it (e.g. with the owner's public key, requiring the owner's private key to decrypt)? Would you call for a court order to demand the decryption key?

Well, since they can get warrants to search someone's house & workplace if they think it's relevant, it's probably not going to be hard to get a warrant to 'search' the black box, and use what they find inside.