I mean unless a computer can check that all dependencies have compatible licenses, that is unrealistic. It's a necessary step for publicly released software to avoid legal issues

Linux distributions (though I can only speak to openSUSE's process) have automated scripts (which I believe are written by our lawyers) which check whether the license of a package matches the license of the files inside the package. It's how most package legal review gets done (and if the script can't figure it out, it gets escalated to our actual lawyers too review. You cannot submit a package to any one of the distributions we ship without the legal review being approved.

So it is clearly possible to do -- and there are all sorts of tools which figure out what SPDX license entries apply for every dependency (or vendored dependency) of a given project.

I took the parent posts to mean that step involved checking the project license, not its dependencies.

For the latter though, Fossology, Scancode etc. can help.

Unfortunately, not everyone acknowledges this truth;)

…or has a sense of humour about it! ;-)