I wouldn’t say “need blind is meaningless”, but numerous reliable sources have referenced admission readers estimating which applicants they believe are SES disadvantaged at need blind Ivy League colleges. For example, the Harvard lawsuit docs state:
Harvard’s admissions officers do not receive information about family income levels, but are asked to identify disadvantaged students during their review of the file based on information they receive about the high school, neighborhood, or other facts volunteered by the applicant.
The Harvard admission reader procedures mention " if the reader has evidence that the applicant may be from a modest economic background, please check “Yes” under Staff Disadvantaged on the Reader Rating Form" and they mention there is an automated value ranging from 0 to 1 that the computer assigns.
Among Harvard applicants, if the applicant gets the SES disadvantaged flag, it was associated with a significantly increased chance of admission compared to otherwise similar applicants who did not receive the SES disadvantaged flag. The Harvard lawsuit docs include an internal Harvard analysis in which the dean of admissions asked the office of institutional research to review if Harvard’s admission system really is able to increase chance of admission for low income applicants while being “need blind”. The review found the following. “Expected” means their model’s expected chance of admission based on application ratings, scores, hooks, and other factors… without considering the SES disadvantaged flag. At time of lawsuit, Harvard seemed to be applying a general boost for being flagged as likely to be SES disadvantaged, rather than specifically focusing on context of test score or test score adjustment.
Less than $40k Income – Expected 6% admit rate, Actually had 11% admit rate
$40-$80k Income – Expected 8% admit rate, Actually had 11% admit rate
$80k-$120k Income – Expected 9% admit rate, Actually had 9% admit rate
$120k-$160k Income – Expected 10% admit rate, Actually had 10% admit rate
$160k-$200k Income – Expected 11% admit rate, Actually had 10% admit rate
More than $200k Income – Expected 13% admit rate, Actually had 12% admit rate
Of course most colleges have a different admission system than Harvard. Most colleges don’t have a $50 billion endowment like Harvard and need to be more concerned about having few enough low income students and/or insufficient enough FA, such that there is enough revenue coming in from tuition to support operations. I expect most colleges do estimate how much tuition revenue they are going to get after FA expenses when they admit a class, as well as have a good idea what portion of admitted class is going to have markers associated with lower SES such as Pell, first gen, … when they admit a class. I expect this to be true both for test require and test optional, which contributes to why highly selective colleges like Harvard usually had little change in such markers when switching to test optional. If Harvard wants x% of class to be “SES disadvantaged”, Pell, first gen, or similar; then they can admit a class that is similar to target regardless of whether tests are required or not. With a 3% admit rate, there are many qualified applicants in these groups to choose from.