It’s a very clumsy analogy, but it does have a fair point. CO2 is a proxy for standard of living, and some countries have a lot more room to cut fat than others.

While China emits almost 3x as much net CO2 as the USA, getting China to the global average emissions of 4.7 tons/person would only have ~1.5x the effect of getting everyone in the US to that level, while affecting over four times as many people.

As a hyperbolic example, getting everyone in the US to be vegetarian half-time with no other lifestyle changes would have roughly the same carbon savings as making the combined populations of Nigeria and Kenya (roughly equal to US population) completely carbon neutral, while also being way more economically feasible.

Ok, you’re maybe 40% of the way to understanding the issue now. First lets look at the two examples you gave.

India has a very high population with lot of inefficient, unregulated high emission light industry, some barely regulated heavy industry, and lots of low-emissions transport such as bikes, buses and trains. This all adds up to having moderate emissions despite their high population. There’s not much room to improve things unless they start cracking down on the light industrial emissions which is difficult(from both policing/regulating and a social/poverty angles).

China as you have pointed out has both very high population and very high emissions. has lots of industrial output hence their high emissions, but they also have extensive low-emissions transport networks with many commuters using pedal bikes, ebikes or PT. They have a bit more room for improvement - they could certainly restrict emissions from industry much better. They could put more effort into switching to more sustainable power generation. There isn’t much they could do about transport though.

Now lets look at three other countries that have come up in this conversation.

Australia has a small population but moderate emissions. While there is a growing percentage of renewable energy, most transport is still via high-pollution petrol and diesel vehicles, causing a lot of emissions. Australia has made some progress but can make a lot of changes to improve in both transport and power generation.

The USA has a high population and also very high emissions. They have high pollution transport, with many oversized and inefficient fossil fuel vehicles. They have high emissions from industry and power generation. The USA has lots of room to make simple changes that would reduce their emissions.

Qatar has a very low population, but ridiculously high emissions for such a small group of people. They burn huge amounts of energy in inefficient transport, because fossil fuels are extremely cheap there and emissions are not regulated. They generate nearly all their energy from high-emissions gas plants, only 0.27% renewable energy despite being ideally located geographically for both solar and wind power. Qatar has lots of room to make basic changes that would lower their emissions drastically.

Now - this is the key part you are struggling to understand - what trend can you observe across all 5 of the countries above, from India to Qatar?

In all these cases, the ratio of emission to population - the emissions per capita - relate directly to how easy it is for each country to make changes that will reduce their emissions. India and China have high net emissions, but its not easy to reduce them when you have a massive population that needs to be warmed, cooled, transported, fed, etc. Australia, the US and especially Qatar could make simple, rapid changes that would drastically cut emissions.

As another person here put it, emissions per capita = how extreme policy and lifestyle changes they have to make to change.