The kin recognition that you mention may be tricky, but kin selection is much more widespread—because there are heuristics that allow organisms to favour their kin without the need to examine them closely—like: “be nice to your nestmates”.
Simple limited dispersal often results in organisms being surrounded by their close kin—and this is a pretty common state of affairs for plants and fungi.
The kin recognition that you mention may be tricky, but kin selection is much more widespread—because there are heuristics that allow organisms to favour their kin without the need to examine them closely—like: “be nice to your nestmates”.
Simple limited dispersal often results in organisms being surrounded by their close kin—and this is a pretty common state of affairs for plants and fungi.