Stanford already has a relatively high minority population, many of whom (and this may be a shock to you) come from families who make over $40,000 a year. In addition, often whites who come lower middle class families get the short end of the stick when it comes to financial aid. Stanford's program will help them the most, IMO.
But like I said, someone has to pay for this. And usually, just as it happens with athletic scholarships, the students who DO pay their tuition have to make up for it.
As many people have told you on this board, Stanford has a very large endownment fund, as does Harvard and Princeton. That is why they can do this, not because of their tuition rates. Duke for instance, charges similar tuition and costs but cannot do this because its endownment is a lot smaller than these other schools.