I suppose because historically countries such as Japan and South Korea have been rather isolated, devoid of expansionist and colonial ambition. On the other hand, Europe has pursued colonialism, interfered in the East and directly caused the disruption and chaos which is leading people to flee on mass scale. Therefore, there is a feeling of responsibility. In addition, a policy of multi-culturism has been imposed on Europe making it quite diverse and It is quite apparent that countries such as Japan and South Korea, who have such strong cultures are not eager to become multicultural.