big corporate donations require 0 engineers, that’s a huge savings

I imagine there could be ways to make their philanthropic donations more efficient. What I'm saying is I doubt they are actually going to donate this amount, and achieve greater impact (however that is measured). I imagine they are going to launch programs that they were already going to launch, donating to whatever charities they favor for other reasons. For example, if they're building a new office somewhere, they can give a bunch of money to charities in that community, to build goodwill in the community.

But these donations are not done purely for altruistic reasons — they're calculated decisions that also help the corporate entity. There's nothing wrong with this, and they'd still be doing good. But it's not the same as letting your customers decide where to donate hundreds of millions of dollars.