
Canonically, the empire conscripts a large portion of it's soldiers from conquered countries. Or, as the Imperials might put it, liberated countries.
While the term brainwashing is thrown around a lot, and it is mentioned by Eorzeans, I'd liken it more to simple conditioning. Garlean soldiers are conditioned to have complete faith in the empire and it's duties. They're likely crammed with propaganda, as the Garleans even attempted to use that strategy to get some Eorzeans to defect and/or surrender to the empire by literally dropping linkpearls directly into the city-states. They don't see themselves as evil, they see themselves as liberators - saving Hydaelyn from the corruption that is the primals. At least, that's the motive we've seen, and honestly there might be some truth behind it.
Now, the manner in which they go about handling said liberation isn't exactly the greatest, but from the eyes of it's soldiers, they're likely rooted in the idea that what they're doing is for the greater good of all the world. They see those that resist (such as Eorzea) as a threat to the safety of the world as a whole because of what they've been told, and what they've grown up with. Thus, they must be stopped.
To the empire, we're essentially the bad guys in the story. We're stopping them from vanquishing the primal threat.
Now, the empire does have other means of "brainwashing", some of which are more sinister than others. For example, Imperial soldiers are actually forced to kill on a daily basis. It's part of their training regimen to slaughter something at least once a day, so that A. they build up a tolerance to killing, and B. it becomes a second nature to them. So they can kill without second guessing themselves. It makes them incredibly ruthless, and incredibly effective.
I could go on, and on, and on about the empire, but I'll stop myself here, barring any further questions.
While the term brainwashing is thrown around a lot, and it is mentioned by Eorzeans, I'd liken it more to simple conditioning. Garlean soldiers are conditioned to have complete faith in the empire and it's duties. They're likely crammed with propaganda, as the Garleans even attempted to use that strategy to get some Eorzeans to defect and/or surrender to the empire by literally dropping linkpearls directly into the city-states. They don't see themselves as evil, they see themselves as liberators - saving Hydaelyn from the corruption that is the primals. At least, that's the motive we've seen, and honestly there might be some truth behind it.
Now, the manner in which they go about handling said liberation isn't exactly the greatest, but from the eyes of it's soldiers, they're likely rooted in the idea that what they're doing is for the greater good of all the world. They see those that resist (such as Eorzea) as a threat to the safety of the world as a whole because of what they've been told, and what they've grown up with. Thus, they must be stopped.
To the empire, we're essentially the bad guys in the story. We're stopping them from vanquishing the primal threat.
Now, the empire does have other means of "brainwashing", some of which are more sinister than others. For example, Imperial soldiers are actually forced to kill on a daily basis. It's part of their training regimen to slaughter something at least once a day, so that A. they build up a tolerance to killing, and B. it becomes a second nature to them. So they can kill without second guessing themselves. It makes them incredibly ruthless, and incredibly effective.
I could go on, and on, and on about the empire, but I'll stop myself here, barring any further questions.