You calculate the carbon emissions per unit of fuel, which is basic chemistry, and you tax the carbon. The whole point of a carbon tax is to avoid value judgeme

You calculate the carbon emissions per unit of fuel, which is basic chemistry, and you tax the carbon. The whole point of a carbon tax is to avoid value judgements about which carbon emission is more acceptable than which. However you mentioned America and Uganda. They would have different tax rates based on agreements between countries. The fact that the US is the largest historical emitter and poorer countries need more flexibility to emit carbon in order to grow is already well established in country to country discussions on this subject. Often the suggestion is that carbon tax funds from historical emitters would partially go to paying poor countries to upgrade to green infrastructure. For example see this 2022 article from the IMF: https://www.imf.org/en/Blogs/Articles/2022/05/19/blog-why-countries-must-cooperate-on-carbon-prices#:~:text=The%20ICPF%20proposal%20sets%20price,%2475%20for%20high%2Dincome%20countries https://www.imf.org/en/Blogs/Articles/2022/05/19/blog-why-co....