It's not a "back door" it's a front door for taxation. It says so on
the tin!
Whatever you want to call it, it explicitly invades people's privacy. It would only gain adoption if the alternative, which is digital cash, is prohibited, in which case privacy in private financial interactions would be criminalized and we would be subject to warrantless mass surveillance.
Bitcoin publishes every transaction anyone has ever done in plaintext.
There are blockchains that don't do that.
This is false.
Can you elaborate? Because I'm certain it's not.
Digital receipts are not a back door.
Many crypto currencies provide a backdoor for hyper capitalists, organized crime, foreign bad actors and tax criminals into our system. It is totally OK IMHO to affront this part of the 'free society' from time to time. Beyond that I would not describe taxability as a backdoor...