The commitments are based on GDP, so it IS related to each country's resources. I'm not saying that Luxembourg should be expected to contribute as much as the US, BG, etc but if you look at GDP of the countries on the chart, it shows that Latvia is pledging and spending far more than France, Italy and several others- their GDP is about $33.5B, whereas France's GDP is around $2.6T and Italy comes in around $1.9T. Latvia has spend more than Germany, where the GDP is over $3.8T.