> Does US anti-discrimination law really operate like "you have to serve the protected class whatever the consequences for unprotected ones?"

“Protected class” is something of a misleading piece of legal jargon; “class”, in it, means something closer to “axis of differentiation” than “group”. [0]

So, “black” is not a “protected class”, “race” is.

(This gets confusing because there is a related concept in Constitutional anti-discrimination jurisprudence of a suspect class, in which “class” does mean “group"; blacks are a suspect class—a group historically subject to discrimination, such that government actions which discriminate against them are subject to strict scrutiny—and whites are not, but both blacks and whites are protected by employment anti-discrimination law because race is a protected class.)

[0] There's a wrinkle in that “age over 40” is an asymetric “protected class” in employment anti-discrimination law.

I think you're confusing "weak and strong classes" with "protected and unprotected classes"

For example, national origin is a protected class and there was a case a few years ago where the EEOC got involved. It was a company owned by Indian-Americans(?) (might have been another nationality) who routinely turned down non-Indian-American job seekers (mostly whites) solely because they where non-Indian-American and they pretty much only hired other Indian-Americans and Indians. This was official policy.

So everyone's national origin is protected, no matter what it is. Everyone is in a protected class.

But say, people who have finger or face tattoos could be turned down for a job solely for having finger and face tattoos because people who have finger and face tattoos aren't a protected class.

Not sure what you mean by 'consequences' for the unprotected classes in this context, but the age discrimination case would only be valid if both the Over-40 candidate and Under-40 candidate were equally qualified, and the Over-40 candidate was rejected solely because they are too close to retirement age.

Note that due to the letter of the EEO law, there is NOT actionable age discrimination if all candidates were over 40, and for example, the 60 year old was rejected in favor of a 41 year old for the same reason as above.

edit: I should also mention IANAL

I think that level of security is only even possible at companies with small codebases or a high degree of siloing. I totally fit this description as a junior with 2 or 3 years experience at my first job where I wrote half the product. At my current job where I've been for 7 or 8 years I can't imagine anyone on any team ever achieving that. Maybe for a little while when you're working in some corner of the codebase that you happen to know really well, but not long term. There's just too many devs making too many changes and nobody "owns" any area. I bet a third to a half of the code I wrote 3 years ago is gone or heavily modified already.

I once worked on a very large project in the healthcare industry. During code reviews you had to provide evidence you did a full impact analysis because the system was so large that not a single person could keep it all in their head. We're talking millions of lines of code. Being senior doesn't make you a superhuman.

You're conflating different things.

If you were hiring an intern and you got two resumes in order to comply with the law you'd have to consider a 60 year old intern still in college the same way you'd consider a 19 year old intern still in college.