That's not true. If you build from a dist tarball, you do not need auto tools installed. You usually do if you build from a git repo, however.
"It" in my post referred to the Rust cargo package in question. The package ships configure.in, but not the generated configure. You do need autoconf for configure.in -> configure. Similarly, it ships Makefile.am, but not the generated Makefile.in for use with configure.
Note how I said "The whole point of autotools is not making your users install them".
No, parent answers the question, "What is the difference between the git tree and a dist tarball?" Which is self-evidently (and unhelpfully) "you don't need autotools installed with the dist tarball". My questions are: Why does this difference exist? Why would you not track everything necessary to build a library in git? How is the dist tarball built differently than just zipping the current git tree?