You having pieces of plastic/paper and/or metal trinkets in your pocket plays will not save you from this.

I understand the apparent privacy angle, but if you analyze it further, cash won't help in the presence of a malicious system. If the government cares enough about you to stop you from using e-cash/credit cards to buy or sell, they will also care enough to not let you roam free.

Hell, even the USSR had paper cash in circulation allowing some privacy and trade between individuals.

Having solely account-based money under complete regulatory control amounts to a huge increase in what is practical to put under political control. It could drastically increase the incentives to ban and regulate trade in anything of interest to special interests. E.g. the pharmaceutical industry could finally get rid of herbal medicine.

You have to worry about both of those things. Why? Because instead of forcing the placement of every steel beam and the sale of every chicken sandwich to pass through the hands of an intermediary who both profits from and regulates the action, we just decided to regularly inspect places where problems were likely to occur, and to investigate reports of possible violations.

The argument you're making would work just as well for recording all human speech at all times, and processing it for suspicious topics - which is totally currently technologically possible. Even if it weren't, why not require that all conversations be had over a telephone? That's pretty much the same as having rules about the amount of arsenic allowed in salt...

Sorry, I'm not buying it.