School Grades- Even Lefties Still Don't Get It

Here's an article from Daily Kos about the relationship between school grades and family income, which focuses on a very legitimate problem, but still doesn't get what is going on.  I don't want to focus blame on Daily Kos, because this response is in agreement with the virtually unanimous opinion you hear from the left:

"No matter how many times people who actually know stuff about education patiently explain to corporate education policy boosters that poverty is the big factor in student outcomes, they wave it off as irrelevant...So let's just grade their schools and teachers like it's within a teacher's power to overcome all that inequality!

Yeah, about that. The Miami Herald has dug into the data on school grades: 

Of the 209 schools in Miami-Dade and Broward with at least 90 percent of students receiving free or reduced lunch, 78 percent received a grade of C or worse. Roughly 39 percent of these high-poverty schools received a D or F.

 Of the 43 local schools with much lower poverty rates (30 percent or fewer students receiving free or reduced lunch), 86 percent received an A, and none received a D or F.

...So teachers in low-income schools are basically punished for being teachers in low-income schools, trying to educate the kids who need help the most."

What is the mistake in this reasoning?  After decades of utter treachery from the Republicans, people are still willing to write this off as an unintended consequence of well-meaning legislation.  That is nonsense.  We should know by now that every action taken by the Republican party is intended for one purpose- to transfer wealth to the rich from all the rest of us.  The No Child Left Behind act, vouchers, every other thing they have advocated as remedies for our schools, has but a single purpose: to provide a justification for transferring money from schools for the poor to schools for the rich.  The inevitable fact that kids with wealthy parents are going to do better in school than kids from poor backgrounds is not taken as a motivation to provide a better education for poor kids- no, the Republican lesson is exactly the opposite- poor kids need to be given a worse education by having their schools' funding cut.  Because, Republicans don't give a damn about anyone but themselves and the rich, greedy vultures who pay to keep them in office.  And because even on the left, lifetimes of being propagandized into buying into the wonderfulness of our "democracy" leaves people unable to accept the degree of treachery that is acceptable on the right.