From Page 6 of the report: “The relationship between essay content and SAT score is strongest for middle-income students and weakest for high-income students.”
Yep - no amount of test prep is going to turn a high income kid with a 1200 SAT into 1400+ scorer. But a one-on-one essay guide , costing upwards of $150/hr, can help turn a mediocre essay into a very good one. I live in an upper-middle class community and the parents here are overjoyed that more colleges are going test-optional. Median HS SAT score for the local HS is low relative to the SES of the community.