I can't type much detail but would surely give you some pointers:
1.Zakat:
Zakat takes money only from wealthy people proportional to their wealth, unlike tax system which even targets poor by direct taxes.
These money is then to be given to those people who have to beg for their survival thus creating a source of livelihood for them. And also it helps those people who barely earn their bread, thus stabilizing and increasing their income. In this manner slowly more people become eligible to pay zakat and the cycle keeps going.
Secondly, unlike Tax, which can be lawfully evaded with help of accountants , Zakat can not be evaded by anyone.