And even Aiel who do serve the Light can have pretty unpleasant beliefs (e.g. they all think Cairhien deserves to be genocided).

In KoD Tylee mentions a battle to put down a rebellion where there were 300 damane on each side.

IMO there has to be way more corruption going on underneath the hood of Seanchan society than we see. Take the Seekers, for example. They're a secret police with arbitrary powers to arrest and put people 'to the question'. Trying to resist them or to escape them is considered a crime. There don't seem to be any limits on who they can arrest, they can use torture to get confessions that are considered valid evidence, and there don't seem to be any limitations on who they can torture (e.g. they don't have to have other witnesses present during the torture, nor do they have to have even circumstantial evidence to justify torturing someone). Consider all the abuses and corruptions real life secret police got up to. There doesn't seem to be anything stopping a Seeker from, say, grabbing some random noble, torturing them into making a false confession of plotting against the Empress, and then collecting the reward from a grateful Empress. Or what about the damane? The word of a damane (or da'covale), according to the Companion, has no legal weight. Thus any accusation by a damane (or da'covale) of mistreatment by anyone will automatically be ignored. Combine that with how much power a sul'dam has over damane (and the ability of a sul'dam to cause a damane as much pain or pleasure as she wants without leaving any physical sign) and you've got a recipe for massive abuse. Especially since, according to Tuon, there are men who rape damane. Imagine what a sul'dam with Semirhage's tastes gets up to in her free time. Or a sul'dam who's willing to sell sexual access to damane to men in exchange for money or political favors. People also tend to gloss over just how awful it is to be da'covale. I think this bit from the Companion illustrates just how bad it can get: And this is done often enough to be considered a cliche. I also wouldn't be surprised if a lot of the High Blood are seriously messed up psychologically. Especially the Imperial Family. You can't grow up in a family where you're encourage to fight against, and kill, your siblings for your mother's favor without getting seriously messed up in the head. I mean, it's canon that two of the Empress's children were arrested and tortured, into making confessions that resulted in them being made da'covale, and their mother thanked the Seeker who did it.

And compulsion is way easier than Turning because you can do it with a single channeler and no Myrdraal. Honestly I think it would have been better if only channelers were vulnerable to Compulsion; non-channelers being immune to mind control would balance out a bit the immense advantages channelers hold over them in every other respect. In regards to why the Shadow doesn't use Turning more often, there are two possible reasons: 1) They'd have to get 13 Myrdraal into the Tower to do it to a lot of people at once, which isn't exactly easy 2) Most of the Black Ajah isn't all that into actually helping the Dark One. They're more focused on their own personal aggrandisement and, pre-canon, thought the whole Last Battle businesses would take place long after they were dead. Turning the Light-side Aes Sedai would actually make them less useful to the Shadow, because those Turned Aes Sedai can now replace them for most stuff, and why would they work to make themselves redundant?