I don't think "get" is normally thought of as an alternative to
the "to be" verb normally found in passive voice, but I've thought
for some time that at least in informal speech it really is.  It
shows the problem with defining passive voice in terms of structure
(to be + past partiple) instead of a transformation or instead of
the agent/agency.  I've also found that a lot of people (not just
academics) react negatively to any use of "got" but I haven't
heard them explain why.  I think that the use of "got" that
bugs people is when it's used as where a "
"to be" verb might be/get used, as in "I got drunk" (which I would
say is not passive voice unless you're a cup of tea).
 
larry beason