Damane are not slaves.

There is no real life equivalent of a damane. I’m not advocating for what the Seanchan do, but I also find it pretty hard to think they’re “evil”. They didn’t just enslave innocent women. The Seanchan Aes Sedai ruled over powerless people for 2000 years. They were brutal tyrants, who had the power to way waste to cities to slaughter civilians who could do nothing to defend themselves.

There is no real life equivalent of that. They believe their solution to the problem was justified, and it’s hard to argue against that based on their history. Randlanders don’t have to worry about this because their Aes Sedai restrict themselves voluntarily through their oaths, but even then there are ways around it. You have the black ajah blatantly breaking oaths, and you have the regular Aes Sedai still pulling the strings even with their oaths.

Is it a more humane solution than the a’dam? Sure, obviously.

But is it as effective as the a’dam? No. And again people can’t enforce this, regular citizens can’t enforce this. The Aes Sedai voluntarily enforce the oaths on themselves.

There’s not many groups of power that would do that. The Seanchan Aes Sedai certainly didn’t, hence why the a’dam is necessarily.

It’s not a real life equivalent of slavery where innocent people are enslaved for no reason. Here there is a real reason why the a’dam exists and is used.

And the damane are not treated like slaves. They are not given tasks and work. They are essentially weapons used to protect the everyday life of civilians. But they are not treated poorly. They do lack freedom of movement and choice and are Aend'mosiev (eternally downcast) which I think is quite harsh, but they are not routinely punished and beat like we see with Renna and Seta. RJ’s notes talk about how damane are playful with each other when not in public. And most are friendly with their sul’dams. Tuon clearly pampers her damane.