Beyond notions of de minimis is the important distinction that copyright does not apply to utilitarian features! There are also notions of expressions that were already in the public domain and some copyright cases even refer to this as prior art.
You boldly assume that all GPL code is trivial and all the functions included in these codebases can be claimed to be on public domain.
There are many GPL licensed codebases (e.g. Linux Kernel, GNU Octave, GNU R, etc.) which contains serious research and novel ideas and implementations. These codebases are esp. licensed that way to keep that research in the open.
I have such a codebase which I was planning to open source with a GPL3.0 license, but I postponed that plans because of GitHub's Copilot shenanigans.
As I said, the code contains many novel, yet short snippets which are worthy of their own research paper.
Downplaying the research embedded in open codebases is just harmful to the discussion.
