We can and do so - in small societies, like inner family and close friends - where trust exists.
So in thery maybe this trust can grow to eventually connect all humanity, but I really would not count on it.
So wouldn't it be nice, if we are all nice to each other? Yes but we ain't. Not with these existing tensions.
Know what the poor world thinks?
"The west got rich by polluting and now we are supposed to stay poor, because polluting is not allowed anymore? Not fair."
And I think they have a point.
When you are starving, you cannot afford to care if the gasoline and coal you are using is causing more long term problems. You are happy, that you have the coal in the first place, if you are cold or need power.
So yes, idealism likely will not solve anything. But it can help make the transition to a sustainable economy.
And I rather would distribute low tech solar cookers and high tech solar panels on scale, than mess with the atmosphere.