Earlier quoted context omitted.
> A less than fun example of this is that the organized labor holiday "May Day" is celebrated in many countries notably excluding the US. Because the US already had Labor Day in September, which predates the May 1 celebration.
That's quite a simplification. Labor day didn't become a holiday until after the May Day vs Labor Day debate started. It started as a concept in 1882 but it was not yet celebrated in any significant capacity and most unions pushed to change the day to May day after the Haymarket massacre in 1886. The first state to make it a holiday (Oregon) didn't do so until a year after the debate was already ongoing and it wouldn…
> Specifically the federal government pushed for Labor day over May day and chose to commemorate the one and not the other with a federal holiday because of fears that memorialising the Haymarket massacre would further empower the labor movement which was at its peak in the US at the time.
It's absolutely absurd to argue that the labor movement was at its peak in the US in the 1890s. This was the era of the Pullman strike--which the government infamously ended by force--and the Sherman Antitrust Act being used against unions under the theory that they were an illegal monopoly on labor. Labor in the US probably reached its peak after WWII. The 1890s were extremely business friendly.
September Labor day preceded May day in both concept (1882 vs 1886) and legal observance. As you noted, the US made September labor day a public holiday in 1894. If you are aware of any country that made May day a public holiday before that time please tell me; I haven't done an exhaustive search, but here's a sampling of when European countries started observing May 1 as a public holiday:
Austria: 1919
France: 1919
Germany: 1933
Russia: 1917
Spain: 1931
Sweden: 1938
UK: 1978