Because almost all the ulema are men and dont care women. In thier fiqhi understanding men 'own' women and thus use and throw as they wish. Notice how legally they favour men and urge them only morally to not to do divorce in ths manner. A man can in a fit of anger or in a drunken state can divorce his wife instaneously. In ahl - hadith school three talaqs are counted as one and hence more compassionate in this regard.