> Why do people think a $1B donation saves $1B in tax?

A distressingly large slice of eligible voters don't even understand how marginal tax rates work. Which is, like, the absolute minimum to have any clue whatsoever how US income taxes are applied, what tax bills will actually do if they become law, and so on. I'd be surprised if understanding of how deductions work is any more widespread.

[EDIT] Not a great source, but it's in-line with the results I've seen from better ones in the past:

https://today.yougov.com/topics/politics/articles-reports/20...

Roughly half don't understand how marginal tax rates work.

Can't find data on how many US adults understand how deductions work, but I doubt it's better.