Well, that sounds slightly better than what we have in the U.S. right now, but I would still argue that taxation is robbery. If a person works hard and earns those 5 houses then they should get to enjoy the fruits of their own labor however they see fit. I might try to *persuade* them to share it or make it available for others, but I don't think they should be *coerced* into it.
Of course, if the society is, at large, Islamic/theocratic in nature, then I can see why the State would be used to enforce certain moral standards. I'm opposed to that--coming from the standpoint of Jewish, Christian, Muslim, or any particular religion. I think the law of the land should be limited to retributive (and not redistributive) justice, what some call "Natural Law," summarized as "don't hurt people and don't take their stuff."
But I appreciate this--I didn't know this is how things worked in an Islamic economy before your note, so thank you. (Ain't nostr great?)