I haven’t done any enough research to know how much this would affect the estimates but I do want to point out that zakat is calculated on wealth, and wealth is not the same thing as GDP (maybe you’re already aware of this and think that GDP is a good enough proxy to estimate wealth).
Yeah the assumption the author makes about Muslim wealth make no sense to me. One can actually look up the GDP of these countries!
I haven’t done any enough research to know how much this would affect the estimates but I do want to point out that zakat is calculated on wealth, and wealth is not the same thing as GDP (maybe you’re already aware of this and think that GDP is a good enough proxy to estimate wealth).