You need to adjust your tin-foil. There is no way for the government to track every single person's purchases unless they outlaw cash. If you think the feds can pull that one off, then I've got a bridge to sell you...
You're forgetting something. The burden of proof is on you, unless you provide in the law that the govt. must prove your spending.
My tinfoil hat is not as thick as the cardboard dunce caps many of you are wearing regarding taxes and government.