It's because there is no meaningful parallel. Conversations are not economic transactions. Period. You can try to stretch analogies ("walking is illegal because of traffic lights!1") but that's stupid and unhelpful.

The Constitution doesn't guarantee a right to private communications. This is the problem. Period. The 4th amendment was sacrificed during the anti-drug/anti-black eighties. Right now the moment information leaves your home -- whether its a phone call or a letter or a bitcoin transaction -- the government has the right to intercept that. They don't even need a warrant in practice.

It's going to require a Constitutional amendment, really a new 4th amendment, that will clearly and unambiguously extend privacy to a person's communication and data. Complaining about taxes on barter isn't going to help and is nothing but distraction.