The Jews could not afford to leave the safety net, provided by their brethren. They simply could not afford the assimilation. Taxation, or rather self-taxation helped to maintain this safety net. It is an old, little known fact that a powerful Polish king granted the Jews the right to maintain separate communities with the right for self-taxation. The taxes saved the Jews from assimilation.
Many religious groups use the tithe method, but on a volunteer basis.
One can pay and one can cheat a little. No Church asks for a copy of the 1040 form. With the Jews it was different, you pay as you are assessed or you are ostracized. The community raised taxes according to its needs, paid by each member according to his means. A committee, of course.