An excellent observation, but I don't agree with your spin.
The US has two loose coalitions instead of parties in the EU sense. Thus, an FU character (Francis Urquart / Frank Underwood) must operate differently in the two settings. In the US, a powerful politician doesn't worry about intra-party discipline, but instead co-ordinates a diverse set of individuals both in and out of Congress, and on both sides of the aisle. The coalitions to move any particular issue forward are quite flexible, and thus FU must be as well.
Both FUs have a clear "reason for existing." In both the US and the UK series, the opening move was a loyal FU being betrayed by the Prime Minister/ President, to which FU responded by manipulating the levers of power. The levers are different, but neither the character nor the motivations are.
In the US " a [Rep] can maneuver to destroy people in his own party for advancement." FU's version of this maneuvering is a bit extreme - in both settings - but peer into the shadows of Congress and you'll see that Kevin Spacey and David Fincher have a lot of raw material to work with. (eg. Paul Teller)