If all things being equal, domestic applicants will be more attractive to programs because
1) There is no visa issue so much better job prospect
2) Better English (duh!)
3) Can be used on marketing materials which attracts more domestic and foreign students alike
4) Diversify the student body
5) More attractive to prospective employers because like it or not, people want to hire someone who look and sound just like them
The list goes on.
Now, "all things being equal" is a very big catch and I expect some programs will scarify a bit of quality to attract domestic students.
So if you are a domestic student and read these unspoken truth, how would you take advantage?
1) There is no excuse for you to not have a great GRE. If you get a 750Q GRE, your color be damned, they are not that into you.
2) Market yourself as a quantitative person who is a career savvy. This means fill your transcript with worthy math/CS courses.
3) Become a frequent reader of industry magazines like WSJ, FT, Economics
4) Become a member of all the quant community and participate in them