It's all about profit now, so a lot of times 3rd parties to the studios get absolutely fucked. I have a friend that edits movie trailers and those people are totally taken advantage of by the studios.
They give the job to the lowest bidder.
The way it works for trailer editors is that they give footage to 20 trailer editing companies, make them all edit trailers, get the trailers turned into them, and then at the end they'll get bids from them all and see which one they want to pick. So 19 of those companies will do the work, but not get paid or get their trailer used. Then the studios won't pay the winning company for years.
Also, think about life of pi. The company that did the effects for that movie, won an oscar for best special effects, which was basically the whole movie, then went out of business because they weren't paid properly.