I don’t see anything in the 16th that requires an “Internal Revenue Service.” I may have read the readers digest version. If you have a flat or fair tax, just let the IRS monitor that. Get rid of all the law enforcement and Obamacare stuff.
Any type of income tax requires an IRS.
FairTax does not require an IRS — the FairTax will collected and remitted by retailers to their respective state sales tax agency, just like the state sales tax is collected and remitted.
Federal oversight of state sales tax agencies is a given, but that agency will have no contact with any individual about his or her tax situation — it will only deal with state sales tax agencies.