It is standard practice to back trailers with excerpts from "appropriate" soundtrack music, regardless of the source. Heavily borrowed music is a sign that the soundtrack is not complete when the trailer was made, usually the case when the film is live-action.
Fully animated features start out with the voices, effects and soundtrack music and visuals are added to synch with the audio. By contrast, live action is filmed first, then the music is recorded with a stopwatch in one hand and a baton in the other. They may start early on composing the music, but they actually record it to synch with the action...the exact opposite of animated film work. In fact, very often there is a large viewscreen above the orchestra pit so the conductor will catch all the subtle nuances of "he's hiding behind the curtain with the knife...she's not aware" or "throw it overboard, it's about to explode!".
Those general assumptions may go out the window IF the butchered editing job of cramming ten kisses, five murders and an exploding car into a short trailer are too disjointed to match up with a proper movie track. Then they might look elsewhere for something to tie this jumble together.
