That map doesn't account for the land area of mountainous terrain in larger countries. Russia and the US for example individually have more mountainous terrain in them than all the mountainous terrain in Europe combined. And the average elevation of the US, 760m (2,500 ft) is split between multiple massive regions with varying elevations. For example average elevation in the US Rockies is between 1500-2100m (5,000-7,000 ft) vs only 100-500m (300-1,600 ft) in the plains and eastern seaboard. The same thing happens in Russia, it's mountainous east levels out because of the flat central and western sections of Russia due to its vastness. A global topographic map would better represent large countries with massive mountainous regions and high elevation areas imo.