I would not be surprised if they all claimed it as a charitable contribution... those go a long way to putting off the tax man.
They would be foolish if they did not.
The tax code tries to encourage charitable giving by making it deductible.
Any change would be devastating to churches and thousands of legitimate charitable organizations.
There's constant whining about "loopholes", but most of them were put in to the tax code for very positive reasons.
Tax "loopholes" are among the very few instances where government can encourage behavior that's beneficial to everyone.
I think the "zero deduction flat tax" would be catastrophic - but it's as likely to happen as a Martian invasion.