> I guess you have more faith than I do that a human vested with these large sums will apply it appropriately.
I agree that humans can be greedy, etc. But that's why we have a judicial system. When you look at history, the Islamic scholars took their faith extremely seriously. Their accounts and biographies are not something you'd find in Western texts, but those exceptional people truly did exist. And because of them, we had things like the Islamic Golden Age.
The governments today have way more money on their hands don't they? Especially with the insane taxation rates we see. You allude to this point when you mention secular welfare systems. But history shows otherwise when Islam was applied.
> Umayyad had a variety of religions of persons overseen by their caliphate
Islam was the dominant religion, and the majority of the population were Muslims. The non-Muslims had to pay Jizya (limited to able men, i.e. not women, children, old men, or religious priests).
One of the categories of people who are eligible to receive Zakat, are those whose hearts are inclined toward Islam. Other than that, I don't think non-Muslims receive it. That being said, poor and needy non-Muslims are definitely eligible for charity (Sadaqah), and it is the responsibility of a functioning government to ensure that its population is well taken care of. Islam guarantees the rights of non-Muslims, and is very strict about it.
> I'd also be interested in seeing the citation that poverty didn't exist under this caliphate.
I didn't claim that no poverty existed in the entire Caliphate. As you know, the Caliphate spanned several regions and districts. I mentioned the Iraqi district, but I came across this question[1], which mentions that the mayors of the Libiyan and Tunisian regions wrote to Umar ibn AbdulAziz that they could not find a needy person to give them Zakat, so he responded to give it to the poor among the Jews and Christians. They replied that still no one took it, and they were no needy among them, so Umar replied to leave it in the market for anyone to take as they need. When still no one took it, Umar ordered to purchase slaves and free them.
I'll have to validate the authenticity of this specific account, but the notion that during Umar's rule, in certain districts there were no poor people left to accept Zakat is established.
> If I wanted to enforce Zakat via inflation, I would mandate people to hold their money in bank
Ah I see. It's prohibited in Islam to hold someone's money against their will, so there goes that :)
[1] https://islamqa.info/ar/answers/182393/%D8%AD%D9%83%D9%85-%D...