Source? Most fundraising events have a deductible and non-deductible portion of the ticket price because the IRS does not look fondly on such practices.
Like the complaints at Liga Chilena Contra la Epilepsia, they just have a Sugerencias y Reclamos book, which you can read (though they told me it is not for me to read). You can see for instance that they addressed one complaint they got a lot, which was the lack of cashiers, so in fact with their remodel five years ago they changed it completely so they now have up to 8 cashiers at a time, and short wait times. My favorite Chilean pharmacy, I'll repeat here the comment I left for that charity: "Un siete!"