As others have said, there's even more at stake with a nonprofit. Charities famously milk their employees dry by emphasizing what good and important work they're doing, to justify overworking and underpaying them. If someone chooses to work for a nonprofit, that should not be interpreted as "willing to be a human doormat".
On the other hand, charities also need to protect themselves from those that are only there to enrich themselves at the expense of the cause - that goes first for the leadership but also applies to regular employees. It's different if you're overpaying someone from profits that would otherwise go to shareholders compared to when you're overpaying someone from donations that people much worth off have spared for your cause.
