I hear ya, but the eighteenth amendment only prohibited "the manufacture, sale, or transportation" of booze . . . not the possession or use thereof. And it's repeal was driven, not only by popular decry, but also by the rapid growth of a black market and the associated crime. The penalties upon the everyday Joe who had a bottle of beer in his house simply weren't there as are proposed for "assault weapons".
Not saying these considerations cover the whole situation, but there are some differences.