The other side is that robbing banks at gunpoint isn't the most effective way to redistribute wealth from those who have it to those to whom it should go.

I suspect that the most efficient way to do that is government seizure- declare that the privately held assets of the bank now belong to the charities. That doesn't work, because the money isn't value, it's a signifier of value, and rewriting the map does not change the territory- if money is forcibly redistributed too much, it loses too much value and the only way to enforce the tax collection is by using the threat of prison and execution- but the jailors and executioners can only be paid by the taxes. Effectively robbing banks to give the money to charity harms everyone significantly, and fails to be better than doing nothing.