Nnnnnnope. The closest to "democracies liking democracies" is that Individualists like Individualists- but an Individualist civilization is not necessarily a democratic one. The ethos-based diplomacy allows a lot more subtlety than a straight up "governments like the same type of governments" one.
EDIT: Look at it this way... there are 4 axis of ethos, each with two opposing points on it. There are only 3 types of government, which exist on one axis. It makes a lot more sense to base opinion modifiers for diplomacy off of the more numerous set of points- the set of points with oppositions- than the one that has only two opposed points and an "in-between".
You do realize that Democratic Crusaders are designed to get a huge diplomatic bonus towards Democracies and a crushing penalty towards Collectivist regimes right?
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