Generally, we would expect that causative verbs (in our case, the unergative and unaccusative verbs) would have a greater degree of overlap of nouns in subject and object position than non-causative transitive verbs (in our case, the object-drop verbs).
since the causative is a transitive use, and the transitive use of unergatives is expected to be rare (see above), we do not expect unergatives to exhibit a high degree of detectable overlap in a corpus.