Not sure how to square that with the fact that there’s been low productivity growth since 2008.

https://ec.europa.eu/eurostat/databrowser and either search or use data code tps00071

UK numbers yes, though maybe gloomy weather plays a role? Just kidding. That said, Brits are slightly more likely to move to Spain than US despite it being a tiny country in comparison and not necessarily easier to move to after Brexit.

Spain, not sure. It’s tricky to compare since non immigrant Spanish speaking population in US is probably significantly lower than Spaniards speaking English. But yeah, you probably have a point on that one.

What language do you think Germans and Spaniards use to do commerce with each other? There needs to be a common language, there’s no bandwidth to learn all languages, so due to historical and modern reasons, English prevailed.

Re Australia, Australians have highly preferential options to move to US which is not reciprocated.

If 50% of Americans spoke Polish by the shake of a wand, I bet there’d be more Americans in Poland than Poles in Poland.

Industrialization, like deindustrialization, is a continuous process. Every industry suffers from depreciation and decay which means that pace of industrialization per unit time matters.

Historically major tax cuts in the US increased GDP growth by -1 to 1.5%.

You bring up a good point but in all realistic scenarios it actually misleads.