Most low-income and even middle-income students cannot meet the academic and experiential benchmarks that elite schools set.
I read someone post that mentioned that the low-income students would less likely be able to do the extra-curricular activities that colleges look for. I never really thought of that, but after thinking about it, it is true. In high school, my parents couldn't afford the cost of all the uniforms, camps, and trips, so I wasn't able to join cheer leading. I remember being disappointed, but realizing that cheer leading was the last thing our money should go to.