We do know that the border had heavy influence for the USA and some countries had concerns as well with an influx of Muslims. Whether the other countries had the same concern as the USA on illegals and a massive flux of different cultures, I don't know...particularly the countries not listed . If they don't, as you imply, then the USA can't fall into the same reason as those that didn't have the same issues, because one other source of variation doesn't exist with the other data. If all the countries were concerned about migration, then that too suggests something other than incumbents losing. So, either take suggests other causes in play potentially for the graph. So I'll throw in the border as an explanation for this year, in addition to the economy, which I believe separates the USA data from the other countries although a cursory review will show other countries had concerns previously as well. There also exists an interaction potential where the constitution may be incompatible with other cultures, that doesn't exist elsewhere? I think the obvious DEI was in play as well in the USA.
So, off the top of my head I believe other things than incumbents just losing because of Covid exists, although I do believe there is a certain segment of people that look towards the government, rather than themselves, that could vote out the incumbents just due to wanting a new person, that they believes heals their afflictions. So I don't just dismiss covid as not having some play.
People can show women making around 23% less money than men, and graph that too, but understanding the significance of other sources of variation also show why that takes place...which are typically choices women make. Then we know the fraud that took place in 2020 and had 15 million less votes for Biden not been registered, placing the total much closer to election totals before, Biden wouldn't have been elected and therefore resulting in an incumbent not running, and taking the USA out of the graph this year.
purdue.rivals.com
