So, sure, the parent could make a different choice, and move to a lower cost of living area, but then they'd be making significantly less, and might still not feel particularly financially secure.
Even now, with many companies realizing that remote work is ok, and planning to allow some form of it permanently, many also plan to change (lower) people's salaries based on where they end up deciding to live, even if they do the exact same work.
Middle class in the Bay Area starts around $150-200k per year.
Where?
I know averages aren't the same as class, but, middle-class would be about half that, if middle-class=average salary, in the USA.
https://www.google.com/search?q=average+starting+salary+in+u...
> While there are a few outliers, the general average salary for college graduates comes to about $50,000
Consider that the US Dept. of Housing and Urban Development considers residents of San Francisco to be "low income" if they make under $82,200 as an individual or $117,400 as a family of four as of 2018[0]. Those numbers are 80% of median income, which means in SF for an individual the median income was about $103k. You said, "if you can earn 100k in your first year you're upper middle at minimum", but, alas, no: if you made $100k in 2018 in San Francisco, you were barely even middle-middle class.
Also consider that making the median wage in your area may still not allow you financial security. We're defining "middle class" here in relation to median wage, which may not be a universal definition. I would expect it has more to do with the median resident's purchasing power.
[0] https://sfgov.org/scorecards/safety-net/poverty-san-francisc...
I'm all for solid wages and better benefits, but let's be honest, a college grad who makes $100k to start is not a middle class wage.
Edit: I should clarify, I'm not saying a new grad _shouldn't_ make that. I'm saying it is not a middle class wage for a someone just entering the market.