Because the united states valued individualism for a very long time, before and during the cold war, and even now. It's a cultural aspect.

Blame people like Reagan and Milton Friedman for this. It's a highly political problem.

Inequality is already somewhat caused by individualism, but climate change is also caused by climate change. For example, if China wants to reduce its co2 emissions, you only have to convince Chinese leaders, and it's done just by snapping fingers.

In the US, you have to make it profitable, which is doable, but it's more complicated and lobbyists will also be a big barrier to change.

I loathe the chinese leadership, but being a democratic modern industrialized nation doesn't mean you will see decisions that make sense.