Is commit seldom used in a passive voice?
well... "commit" (like any other verb that can have an object) CAN be used in passive forms.
e.g.,
The agency cancelled the project, wasting the resources that had already been committed to it.(= someone/some organization
had committed these resources. since the identity of that/those entities is unimportant here, the passive is a good way to write this sentence.)
as for your question about "seldom"... well, i'm just going to leave that one unanswered, since i can't see how there could be any value in quantifying such a thing.
it's a thing; it exists; it's possible. that's really all that is worth knowing here.