It's you who doesn't understand the Constitution. Criminal law was to be entirely left to the states, not the federal government. The Bill of Rights is there to protect against violations by government. Otherwise, every murder that occurs anywhere in the country would become a federal case.
They have federal criminal law there.
George Washington's first crisis involved taking the army out to collect whiskey taxes.
There are numerous elements about taxes in the Constitution, and they necessarily imply collection methods, use of law, courts, etc. Don't pay your taxes and we use federal criminal law on your tail.