Carnivorous plants are just plants with a special set of characters that allow them to use animals for food. There is nothing they do that some other plant or plants cannot do. It is the package of traits that define what is carnivorous and what is not.
Many plants kill animals in a body present way. That does not mean they are carnivorous. Or semi-carnivorous. Or proto-carnivorous. Or whaterver-carnivorous. They are just murderous.
Carnivorous plants can have simple traps or elaborate traps. Whatever works, works for them.
Benefiting from trapped prey is the hallmark of true carnivory. How do we know when a plant benefits?
There are costs to carnivory that plants must pay. These costs can be high and not all carnivores are all carnivorous all the time.