Let me also add, wrt portfolios, that yes, indeed this DOES favor those families with high SES.
Even if students have equal ABILITY/POTENTIAL, it's pretty clear which come from a families where outside activities cannot involve additional monies or parental TIME.
Also clear which of them come from a families where both money and time are not much of an object.
SES matters. It just does. It particularly matters in the fine and performing arts and in STEM, where resources in lower-income schools may compound the problem because they are frequently not seen as "core" missions, and are ill-funded and poorly maintained.
Parents who work in non-salaried, low-wage jobs can't necessarily get kids to even 'free' opportunities. Seriously, I hear "there are free opportunities" and I think, "Wow... 'let them eat cake,' much?" My parents couldn't take the time to get me to a lot of extracurricular things, even when they were affordable. Mostly, if it didn't happen through school-- it didn't happen. I don't even know how my DD would have the opportunities that she does without a parent who doesn't work full-time. That would not be possible if my DH and I both made $12 an hour and worked a job and a half each.
So yes, IMO, portfolios are an even more disparate thing than standardized testing is, just as Bostonian noted.
THIS.
And I'll add that even in public, "all children are theoretically equal" school programs, some are still more equal than others. A shining example would be the sixth grade math teacher (fulltime gifted magnet) who asked parents to furnish graphing calculators. She couldn't require them, of course, because then the school would have to furnish them. But it was strongly suggested.
