Why does per capita matter when it’s the total emissions that we actually care about?

Wonderful, the United States uses more per capita than anyone else. That doesn’t mean anything in terms of total warming. Even if we cut to zero we still continue.

Maybe co2 per gdp per capita? Who generates the most wealth while emitting the least co2.

Per capita doesn't mean nearly as much as total. If the countries above the US were instead on par or below the US as it relates to totals, we wouldn't have the same issue we have now.