the more carnivorous a plant is, the less conventional its habitat is likely to be. venus flytraps live in a very specialised habitat, whereas less carnivorous plants ("byblis", "pinguicula") are found in less unusual habitats (i.e., those typical for non-carnivores). "byblis" and "drosophyllum" both come from relatively arid regions and are both passive flypapers, arguably the lowest maintenance form of trap. venus flytraps filter their prey using the teeth around the trap's edge, so as not to waste energy on hard-to-digest prey. in evolution, laziness pays, because energy can be used for reproduction, and short-term benefits in reproduction will outweigh long-term benefits in anything else.