While the wikipedia page you cite does have a section heading called “1945-1992”, that’s only because it uses WW2 and the EU treaty as endpoints. Not because laws were being passed in 1945. Moreover, the cited page doesn’t list country-level laws in 1945-1992, it lists international treaties; and the earliest listed treaty is from 1953.
Because the US law was passed in 1990.
European countries had disability laws passed in 1945
While the wikipedia page you cite does have a section heading called “1945-1992”, that’s only because it uses WW2 and the EU treaty as endpoints. Not because laws were being passed in 1945. Moreover, the cited page doesn’t list country-level laws in 1945-1992, it lists international treaties; and the earliest listed treaty is from 1953.