Are you sure that it’s telling parents to beat their children and not just explaining when and how to use a smack so that children learn? Personally, I believe that for certain behaviour such as dangerous or repeated chutzpa and unreasonability from a child deserves a smack, as long as it is given infrequently, in private (so as not to embarrass the child) and not in anger.
I do think that amazon would draw the line on material that bordered on child abuse.