In the first case, to avoid the penalty of being fined, you pay taxes.
In the second case, to avoid the penalty of being taxed, you don’t donate.
If I allow you to donate without being taxed, it doesn’t follow that you will donate. Maybe you don’t want to donate to begin with, or not unless everyone else does as well. That’s the model the OP assumes.
Tax rates on non-donation gifts (= marginal income taxes of the non-rich) are “only” a few tens of percents. For the OP’s model to work, he had to assume a ratio of 1:1,000,000 between the value to a noble of keeping or donating money. That’s as if there was a 99.999,999,9% tax rate on donations! If there was such a tax rate, then making donations tax-free would certainly stimulate a lot of donations. But as it is, under the OP’s general assumptions, tax rates of ~~ 30% should not much matter.
I don’t see how that is applicable.
In the first case, to avoid the penalty of being fined, you pay taxes.
In the second case, to avoid the penalty of being taxed, you don’t donate.
If I allow you to donate without being taxed, it doesn’t follow that you will donate. Maybe you don’t want to donate to begin with, or not unless everyone else does as well. That’s the model the OP assumes.
Tax rates on non-donation gifts (= marginal income taxes of the non-rich) are “only” a few tens of percents. For the OP’s model to work, he had to assume a ratio of 1:1,000,000 between the value to a noble of keeping or donating money. That’s as if there was a 99.999,999,9% tax rate on donations! If there was such a tax rate, then making donations tax-free would certainly stimulate a lot of donations. But as it is, under the OP’s general assumptions, tax rates of ~~ 30% should not much matter.