I should indeed have clarified that the browser web has a much richer set of headers and response codes in use, and they are truly useful, and anyone serving we

I should indeed have clarified that the browser web has a much richer set of headers and response codes in use, and they are truly useful, and anyone serving web pages at scale should indeed learn about them. IIRC it's still about 1/3rd to 1/4th of the nominally defined HTTP response codes that are useful, but it's still something. The non-browser web, they approach useless. Which I'm not happy about and not celebrating or advocating for. It's just how it is.