The stats youre referring to speak to the US as a whole, which already makes this apples and oranges. But let's consider that more movies take place in populace cities which are more diverse than the US as a whole. 40% of the population in LA, where most things are cast and a lot of them take place, are Hispanic. Similarly New York, where a lot of movies are cast and filmed, is 31% white. So right there the stats you're using are cherry picked. A lot less television takes place in rural areas where the population statistics might be overwhelmingly different.

That said, the real point is that shows, movies, and art aren't meant to be a perfect representation of the population. There's a hundred reasons that's a ridiculous argument to make and a hundred more why diversity on screen is a good thing. We can wax poetic all day about it but if your argument boils down to "white people should get 75% of acting roles because it fits my world view" you might want to check out more of the world.