Does tying loans to major earnings ever work out for the students it's supposed to protect?

I finished paying my student loans off three years ago, software job, on paper I'm the success story the tie-loans-to-earnings crowd points at. what the paper doesn't show is that I enrolled as a music education major, because at 18 that was the only thing I could imagine wanting to be, and if the loan had been locked to that major's projected earnings I never get to make the switch at 20 that my entire career came from.

the switch wasn't even a grand plan. I panicked about money sophomore year, transferred into the CS program, and the class that taught me the thing I'm actually paid for was an elective everyone called a blow-off, where the professor made us rewrite every argument until it collapsed or held. I write the design docs now. my salary has very little to do with anything a projection could have scored when I was 18.

the pitch for tying loans to major earnings is that it protects working kids from debt. but the formula only gates the kids who need the loans. the ones with parents who can float a sociology degree never meet the screen, they just study what they want. so the kid from the family where nobody's filled out the form before gets her choices narrowed to whatever the projection liked that year, at 18, before a single class has shown her what she's actually good at.

I get the fiscal argument, loans that never get repaid help nobody, and a slower version with real grandfathering is less bad than what's on the table. just stuck on how nobody who changed majors sophomore year, or at 23, or ever, is in the room when the screen gets designed. What would you build into it so the switchers and the late ones don't get priced out of the finding-out part?