The fact that liberals now want to use "income" as the yardstick makes it less complex, don't you think? Simply stated, this is an attempt to force people to send their kids to(in many cases)schools that have "poorer" students, even though parents most usually would prefer to send their kids to schools with "richer" students. Like, lets all pretend all students, regardless of backgound "behave" similarly..
Oh, and anyone who thinks forced integration "can" work, merely has to look at liberal administered Prince Georges County in Maryland where the percentage of White students in the Public Schools dropped from 77 % to 23 % in 12 years. Why should I buy an expensive house in Laurel and send my kids off to a school where their safety can't be assured (even though safety is probably the authorities number 1 concern, by far)
People send their kids to school in the hope that they'll get a good education - meaning not just math, reading, and writing, but also social values and social partners. In a society as diverse and mobile as ours many factors contribute to the success or failure of such an enterprise; race, religion, ethnicity, social class, home-life, individual ability and determination, and - very important but often neglected - history. It can be difficult to discard a dhimmi relationship - for both masters and subjects.
Forced integration has run its course. It benefitted some and hurt more. It's time to try something else.