For a lot of movies, the home DVD/Blu-ray release is getting a lot of attention. Many times, they are mixing the theatrical release's audio in a full theater-sized dubbing stage and then they are mixing the home release in a completely separate, small dubbing stage.
So it's often not a case of having identical audio to the theatrical release and often not even a case of just taking the theatrical release and EQ'ing it. It's actually a case of re-mixing the soundtrack as basically a totally new recording - based off of the theatrical release, yes, but made in a totally different room and environment and with different equipment and different sonic goals in mind.