That automatic withdrawal idea would actually be a great idea absolutely as you stated to help people donate to causes like charities. In my experience, it's not that people aren't caring or compassionate, it's simply that they are forgetful or they just need that extra push or motivation to take action on a initiative like donating to a great cause. A automatic withdrawal idea could help with that.
Charities are learning now that they need to set up automatic capabilities for their supporters, because with so much drawing our attention daily, it is hard to remember one thing out of a thousand.