Ultimately, Benson’s algorithm is not meant to classify life/death or the presence of eyes in a broader, general sense, but rather a more narrow definition of “pass-alive” or “unconditionally alive” groups, which refers to which stones cannot be captured even if the other player only passes.
When we usually speak about the general strategic notion of life, death, and eyes, we typically talk about a broader set of situations.
For example, in the below position, we would typically say that Black is settled and alive, since White cannot prevent Black from making two eyes, even if White plays first:
However, this position is not “unconditionally alive” (or “pass alive”), in the specific technical sense dealt with by Benson’s algorithm.
Note that in common discussion, Go players may often call the above position “unconditionally alive”, but they are using this phrase in a different sense (that Black is alive, regardless of who plays first).