It's not just society, it's also biology. Even if "parenting" roles were completely equal, "childbirth" role would fall only on women, so they would still take more time off for children (and hence get lower pay).
If only pay gap were proportional... I'm afraid that employers penalize time off work disproportionally, probably exponentially; part-time work doesn't have half the salary of full-time work, and when employees take a few weeks off, they don't forgo only those weeks' salary, but also slow down their future learning, progress and promotions. Whether that's fair or not is debatable (I'd say it makes sense from employers' point of view, but they're probably unnecessarily harsh with it for game-theoretical reasons), but it probably affects all employees taking time off equally, not just women.
Don Quixote would be proud of those who hoist their flags in battle against evolution, biology and the laws of the universe itself.
Keep up the good fight, dear gender abolitionists, for you truly are against a formidable foe.
1. Attempting to fix the problems of the women in their circle and the resulting echo chamber effect.
These men feel guilty when they hear/see women getting into a victim complex or when they are uncomfortable with market forces.
I keep asking my wife & women I know to demand higher salaries and they are content to take the easy non-confrontational path.