The century-old idea of Jantelagen helps explain why Scandinavian cultures prize equality and egalitarian behavior. Building a culture that prizes social welfare, a degree of conformity, and introduces a negative pressure not to distinguish yourself too much from the crowd. There’s another interesting article on it here: https://www.scandinaviastandard.com/what-is-janteloven-the-law-of-jante/
The book it originates from was written by a Norwegian author who lived in Denmark. Jante is in Denmark.
Janteloven absolutely exists in both Denmark and Norway, but it takes on different forms. My personal impression is that it’s more hardcore in Denmark - you really should not stand out, to the point where people are extremely uncomfortable with voicing disagreements or standing out in any way. I think Danish xenophobia might also originate partly in Janteloven.
As a Norwegian in Denmark I’m used to dealing with the quirks of Norwegian society, but I find Danish society to be hard to navigate. There are good and bad sides to the law of Jante.