Daemon:
Since asking for receipts is too invasive, is that why companies like Walmart forcing all their suppliers to implant RFID's in all their products?
There appears to be no provision to deactivate those implants - at least none that I've heard of. They would be useful while checking reciepts at the door, but it's primarily a way to check in merchandise, and then check it out when sold.
Bar codes do essentially the same job - this is really a non-contact/no-visibility version of the bar code.
The folks who are concerned about privacy feel that these implants can be read at fairly long distances (like somebody driving down their street and learning what brand of toothpaste they're using). Or, you could be scanned unobtrusively to see what brand of underwear you're wearing, and have that recorded, somehow - perhaps to direct you to the shelves selling another brand.
Is this an invasion of privacy? Yeah - I think so, but the grocery stores already "profile" people who use their "discount cards", and it'd be easy for the average Best Buy (for example) to record what you bought there.
Bringing that data together (I.e., combining what you by at WalMart with what you buy at Best Buy and Sears, etc.) is what bothers me.
Guess the good news is that it'll be used to target advertising, IMHO, rather than anything more nefarious.
I hope....
(Besides my rent-a-cop experience, I'm a Computer Consultant. One of my specialties is inventory control for small businesses - bar code printers & readers.)