My discipline is conference-heavy; all the copyediting and layout generally falls to assorted grad students and other underlings at whichever institution hosts the particular conference that year.

The major publishers (who need to get involved to have the proceedings indexed and "counted") get everything ready to publish online (well, they do slap a cover on the thing and get an ISBN) after the review process and technical process is done, and still try charge for access to the articles.