The sentence that I am writing is
Such a presumption assumes [sameness] in political dynamics across countries which is certainly not true.
The intended meaning is, to point out the person's argument is derived from the notion that politics in countries are more or less same, so laws in one country are suitable for another.
However, the phrase "sameness in political dynamics" does not seem sensible. Seeming is certainly subjective and thus I don't really have evidence to demonstrate why it is insensible. So please let me know if it goes with the context, and if it doesn't what a better alternative could be?