It would be, if all kids were mythical blank slates of equal ability. But all the evidence is that they're not; they carry in a lot of economic and cultural baggage.

To quote the superintendent of public instruction, 'So why do we have these different subgroups? Because we're starting with black children where they are. We can't start them at the 82 percentile because they're not there.'

It'd be nice to say that a 100% pass rate is the only acceptable outcome, but the reality is that you can't achieve that in the short term. So you can either a) label everyone who falls short a failure from the outset, or b) set realistic goals for different groups, allocate resources accordingly, and aim to reduce the gap every year until the passing rates for different groups converge to less than a single standard deviation.

It doesn't matter whether you're looking at scores or passing rates. Your objective is year-on-year improvement. I think this is both more honest and more desirable than declaring educational institutions to be 'failing schools' and tarnishing the reputation of everyone who works or attends those schools.