A way to look at how this plant can attract animals, is to see how it fits in an ecosystem. Plants (and animals) are interconnected... so the way it attracts food could possibly lure a human, as well. But you have to think, if the plant is aware of the threat of humans... then they would also have to adapt to that as well. So then the issue of survival is tied in with this question (I would think it's implied, but then again it may be irrelevant because you didn't specify how many humans live on this planet... but for sake of the answer, let's just say it's well inhabited by humans).
so let's address the survival part first:
Best way for this "plant" to survive is to be adapted enough to ward off the threat of an apex predator/species. If humans knew the danger of such a plant, surely the would burn them all, unless there is some reason to keep them.
I would think that this plant, as large as it is, would have to camouflage with other plants in it's habitat somehow. One way I can think of, is that it is intelligent enough to self-graph itself - break off one of it's branches and attach a different plants branch to it... eventually looking similar to the one's around it.
Living Spiritual Icon
You didn't specify what kind of plant this is, but let's just say it's a tree just because of it's size. If you are in Asia, you'll notice large trees have shrines around them, and have some kind of "holy wrap" around them (forgive me I can't think of the word for it off hand). But I've heard the reason for this is that it is a house for spirits. This could be one reason why people won't try to irradiate this carnivorous plant. Perhaps there are cults that worship it... or give sacrifices to it.
What better way to attract prey then produce some succulent sweet tasting fruit? Even better if it looks similar to other plants that are not carnivorous... which would explain a human inadvertently getting eaten by one. Can also explain how it tricks other animals, like an elephant.
I didn't see the comment before that it's a vine. Graphing is more for trees, but with a vine perhaps it could blend in with plants/vegetables... like a kind of giant pumpkin or cucumber! Still... these concepts could apply. Maybe not the spiritual association part though.