Talking here about "earthworm diversity", is another thing that is wrong.

To identify earthworms is difficult even for experienced taxonomists and you need a microscope, a disection table and a lot of training. Polychaetes are much easier by comparison and I can assure you that they aren't easy. You need months of study.

Not, not everybody can do the work of a biologist. Not even the smartest children. Is complex, and hard work. Unless you want to classify the diversity of worms into "small", "medium sized" and "big worm", dig a hole and count isn't enough.