Opposition in North Africa, the Middle East and parts of South and South East Asia is at least partially explained by religious political ideology.
Russia, as the biggest area, and China might be fueled by opposition to their percieved cultural enemies.
I don’t know why India and Japan haven’t legalised marriage equality yet.
India? the country with deeply rooted religious society that has little regard for women in general? that India would go for equality?
A 2023 Pew survey found 53% of Indians being for recognizing same sex marriage and 43% against (for comparison Switzerland in their 2021 referendum had 64% for and 36% against same sex marriage).
India relatively recently decriminalized gay sex and passed a law legally recognizing the gender trans people choose to identify as, and the national health insurance covers abortions and transitioning.
Its not as simple as your comment makes it out to be, equality in marriage might sometime be recognized.