You miss the fact that most of these parliamentary systems are dominated by the small minority of the propertied. In all capitalist countries, it's money that talks -- unless alternative forces such as labor are well organized. But these days, the latter counteracting force just isn't there. Even "social democratic" political parties such as British Labour end up being capitalist parties. In poorer countries, they mostly operate under the Iron Thumb of the International Monetary Fund or Thomas Friedman's Electronic Herd.
In other words, it's a mistake to conflate "parliamentary" with democratic systems. -- Jim Devine "Science is the belief in the ignorance of the experts" -- Richard Feynman