Reasons why Hollywood sometimes casts a black parent with a white child.
As we see in San Andreas - Dwayne Johnson is a black dude (to be more detailed - he's black and samoan) and the teenage daughter is Caucasian with no black features whatsoever. Hollywood has done this a few times (example the Jennifer Lopez movie "Enough", the daughter was white and JLo is clearly Latino, they also did that with the other Dwayne Johnson movie "Snitch" his son was Caucasian with no black features) The reason why Hollywood sometimes does this is because of laziness, they think it isn't relevant to the movie, when it actually is (you cast a black parent with a white child, viewers are not going to take the film seriously and they'll be focused on the odd parent / child situation rather than the movie itself).
Hollywood already spends millions of dollars on a motion picture, they may as well make the extra effort to get the characters right, if you cast an actor with black features, make sure the child has at least one black feature (example curly hair, or a wide nose or big lips) as a Black British person i'm sick of the wrong casting in some of these films as well.
Another reason why Hollywood sometimes miscasts actors like that is because the casting director is willing to overlook the faults in favour of getting eye candy or A-Listers in their films, a lot of people find Alexandra Daddario attractive, so they cast her in that role to get male viewers, it's silly because the movie would have still done well at the box office with a part black / part white / part samoan actress as the daughter.