(1) All banks, trust companies, and Morris Plan banks now or hereafter chartered under the laws of the state shall have the same immunity from state and local taxation that national banking associations have from time to time under the statutes of the United States.
(2) All credit unions now or hereafter chartered under the laws of the state shall have the same immunity from state and local taxation that federally chartered credit unions have from time to time under the statutes of the United States.
(3) No tax may be imposed by the state or any of its political subdivisions on any savings and loan association or its franchise, surplus, deposits, assets, reserves, loans, or income which is greater than the least onerous imposed by the state on any other financial institution as defined in chapter 658.