It's a real problem! Every agent right now has their own weird filename. I love David Crawshaw's sketch.dev, but for reasons passing understanding they choose "dear_llm.md" for theirs.
edit: They're on it. Not everything has to be complex; sometimes somebody just has to do it.
CONTRIBUTING.md is not a standard: it’s a convention pushed by one platform, used by some projects (but many more will not write down such information, or put it in a README file, or put it in some other documentation).
LICENSE is definitely not a standard: it’s one of a wide variety of names people use to hold licensing information, which some tools will be able to detect. I just looked through my /usr/share/licenses, of 1135 files, only 300 are named LICENSE—it’s the most popular single name, sure, with COPYING next at 182, but it’s still definitely a minority, though in certain ecosystems it may be more popular. Any license-detection tooling will be scanning for a lot more file names. “LICENSE” is a very weak convention, compared with the others.
It makes no sense and it really needs standardisation. I hope this catches on.