Someone Should Tell Them

This problem, this situation that you mention in your question appears to have a relevant place in our world. Whether it be now, 5, 10, or 300 years from now; this virtual reality of a hostile takeover of our privacy is plausible and may become our reality. Yet in this insecure world where most of the human beings on the planet being are being manipulated to sign up for a rewards card and actually believe it is just a rewards card. It is not common knowledge that their purchases are being tracked. Their every move studied, analyzed, and decrypted.
This is where the problem lies, but an education of what the companies are actually doing for those unknowing people who simply want a free trip to that hot, hot island that lies just down south might just change their opinions on these cards. Would cardholders freely give up this knowledge if they knew what was really happening? Or would they feel that this is an intrusion of their privacy. I believe it is that latter and the problem remains that people do not know they are being tracked.
As more and more of these rewards programs become popular; it seems that we as humans will be increasingly more desensitized to the surveillance that is already lingering everywhere we go.
As common sense has always said (or maybe just my mothers words), "nothing in life is free". We have to give to receive and that will be forever entrenched in our beliefs, and so for the heads of the rewards companies, they are doing nothing wrong.