That kind of blood dishes have been made everywhere in the world. So long as you have people that try to use everything on the animal to feed themselves or sell, these kind of dishes exist.
Ofc, it simply could be that they never thought of the reason considering they don't seem to be those extravagant vampires you usually see, but clumsy village folk with aversion to the sun
Still, even then, this is bit of a stretch. ^_^,