Kernel yes, but coreutils? It’s ls, sleep, who, pwd, and so on.

I know, but do they? Has big tech contributed to the code base significantly for coreutils specifically? sed and awk or ls has been the same as long as I remember, utf8 support has been added, but I doubt apple or google was behind that.

Do large tech companies contribute a lot to the GPL coreutils?

If the only tool you have is a hammer, it is tempting to treat everything as if it were a nail.