Speaking as someone who used to work on Microsoft's CETS - it was driven by an undertsanding that if you provide a platform and ecosystem, you have some level of responsibility to prevent and/or mitigate the harms that occur, or may occur.

I personally haven't seen any charitable or notable contributions by Facebook, Google in those spaces (i.e. slavery, human trafficking or child exploitation) - admitedly, I could have missed news on their efforts.