Zakat/alms is a personal responsibility, a Quranic obligation as you know and income tax would create double-dipping out of the individual's pocket, since in Democracy, the state assumes varying degrees of responsibility for orphans, the infirm, cripples, etc. From a mere economic perspective, the more booty/plunder that can be obtained, the more can be given via Zakat - an economic consideration in the expansion of the Ummah.
Zakat can also be collected and administered by the Islamic state. Muslim states throughout history generally have found little difficulty in collecting taxes. You can find a decent discussion of taxation and Islamic history in Ibn Khaldun's Muqaddima. Note once again that income taxes are an innovation in Western practice, only lately levied, just as women's rights are comparative latecomers in the history of liberalism.

The Islamic world hasn't yet resolved the issues of honor killing and clitorectomy for example, even in areas that are semi industrialized. In the epitome of industrialization in the Islamic world, Saudi Arabia, women can't even drive cars. Rigid paternalism is sanctioned in Al Qu'ran, there is no way around that. The prescription for divorce, punishment for adultery, property division, the authorization for multiple wives etc are fully paternal.
Honor killing is most often found in clan, tribal, or caste-based societies and are hardly restricted to Muslim countries. They are, for example, a major problem in democratic India among all religious groups. See also, for instance, a recent occurrence in Catholic Italy. The same goes for female genital mutilation, which largely continues as a sub-Saharan African practice and is common in Christian as well as Muslim countries in Africa - for example Ethiopia, where the Coptic Church sanctifies the practice.