In an effort to reduce the blowback of popular outrage against lethal repressive techniques being used against citizens protesting, democracies pioneered the creation of non-lethal activities like light grenades, rubber bullets and the like. This reduced blowback from the event as it could be shown that governments were being careful and not especially brutal. This also reduced blowback because these new techniques quite frequently did not leave any physical evidence. Hard to have a photo op with no bruises or blood.
Once the industry was created, there was an interest in developing an export industry on the product (see the table from the Omega Foundation report above; full report provided here). This is where the repressive entrepeneurial spirit "kicked in" and globally distributed their wares as well as an increase in the global use of related repressive activities. Interesting, there is little scholarship that talks about whether democratic countries are associated with diverse forms of repression outside of their borders. As one of the strongest findings in the social sciences is still that democracies do not fight one another and that they are generally less repressive against their own citizens than autocracies, this is perhaps the new frontier or with the School of the Americas simply a new version of some old arguments - some know how to repress and teach as well as supply others to do it as well.