Isn't it the other way around? Looking at fraction of GDP controls for size of the country, since large countries have more unemployed people because unemployment rates don't differ by orders of magnitude.

The unemployment rate in the US and Germany are very similar (4-5%), so Germany spends 7 times as much training per unemployed person.

No, the problem with percent of gdp is that it doesn't account for gdp per capita differences.

But all the countries we're comparing to are developed economies with similar GDP per capita.