If your imagination is so limited as to not realize the implications of this, then I suggest that you either increase the dosage of your medication, or allow this technology to invade your life. Either way your horizons will soon be expanded Most rational people however are trying to protect their privacy and not take it so much for granted. Live without it and you'll soon understand.
And if you are so worried about getting unsolicited email, then I suggest that you either get a proper email client, disconnect from the Internet or power level your IQ abit.
Besides, who said anything about RFID being implanted in the items you buy? The way I heard it is that it would only be used for identification as well as a credit card.
Of course, you COULD implant chips that read your fingerprints into everything you buy and sends this information to "the government" thus letting them send you targetted ...gum advertisements (XD)... nah I can't continue this, it's just too retarded XD
Either ways, you will soon realise that nobody has been able to offer a valid point as to why the police and hackers shouldn't have access to this information.
Here in Norway there are surveillance cameras inside pretty much every store/bank/corp office, and also in major public areas where alot of illegal activites take place. I've yet to hear about anyone who cares. It always saddens me when there's some narrow minded Americans with thick Louisiana accents going "Whell, I don't care much for them fancy 'techno logi' crap. There's all them talk about 'hackers' about, an I don't want nobody seein' what I'm doin out them barn late at night!"
Humanity will never evolve if those kind of people are to decide what's to happen. New technology may not be perfect (who could ring their mates in South Africa when the phone first was invented) but it's the only way forward.
Oh, and PS: The ident theft issue could be circumvented by having the chip reading your DNA as well, as I doubt that could be faked as easily.