[moate]

As the article points out: If conditions exist for "high-quality plant growth" (correct light, soil, moisture, etc) then plants don't make weird adaptations like eating things/water-conservation methods.

However, if those conditions DON'T exist, then it's hard for plants to get very big.

There's also this: the larger a moving creature you're trying to capture, the more resources you need to invest in the trap. Bladderwort exists everywhere because it's easy to trap small/microscopic things. Giant bear-eating plants exist nowhere because consistently trapping a bear with just leaves, sap, and stems is really fucking hard.

At a certain point, the plants reach an equilibrium where the effort is worth the end result, but diminishing returns if they got larger.

[ahartmetz]

One can imagine some pretty twisted stuff, but anyway large mammals tend to have enough brains to learn to recognize dangers without, or failing that, with evolution (think innate fear of snakes).

[HelloNurse]

Consider plausible interactions, like cow vs. sundew. The sundew's only hope for survival is looking inedible and repelling the cow, capturing the cow is completely out of the question.