I realize this may seem like mob-mentality or mob-rule but there's some nuance here. When you see such gross negligence do you wait until hearings and court judgements which can easily take years before voting with your wallet?
I'm already trying to figure out how to push locally for dropping SSNs from processes, no matter how Sisyphean it feels.
The way to "opt-out" is to never use credit.
In most of the US it's against code to live in an apartment without electricity. In order to get electricity, you have to open an account with a utility, who opts-in to submit all your data to Equifax.
Their Workforce Solutions division does the same thing with employment data-- so simply by applying for a job from a participating employer, you're consenting to ultimately let the employer report that you work for them, what your current salary is, your SSN and all the rest of the juicy PII.
Fall on hard times? Need some government assistance? Applying for food stamps will also result in your state agency making an inquiry with Equifax to confirm your location of residence and last reported income. If you didn't have a profile before, you do now.
There is no way to opt out unless you work for yourself, live in a home you paid cash for, generate your own power/gas, and never use credit. So basically Unabomber life.
For me personally, the trading issue is a related but separate incident; one hasn't crossed the same threshold of clear evidence.