All special tax bills issued for special assessments for constructing sidewalks and roadways as authorized by sections 231.400 to 231.420 shall be assignable and collectible in the name of the county, to the use of the holder thereof; but the county shall not in any event be liable for any costs that may accrue in such action. Such special tax bills, in any action thereon, shall be prima facie evidence of the regularity of the proceedings for such special assessment, of the validity of the bill, of the doing of the work, and of the furnishing of the materials charged for, and of the liability of the property to the charge stated in the bill.