The option to spend money the planetary good has always been there. It's only rarely been considered in the US.

Instead a lot of 'aid' spending is often tied to marketista missionary work in developing countries, on propping up corrupt regimes, and on fighting communism back when that was still fashionable.

I think there's a useful but modest contribution from private sources in the US. But private philanthropy rarely takes the global view and is too unreliable as a funding source to support structural improvements.

The US is also famously indifferent to, and sometimes actively hostile to, the UN and its various humanitarian projects.