I specifically mentioned mutually tail recursive functions. Self-recursive functions, like what you're describing, are much less useful or interesting.

I say that as a Scala developer that loves Scala and the JVM - the lack of tail calls optimization at the JVM level is a pain in the ass, because in order to work around it you have to effectively build your own call stack.

It's not exactly an error. Neither language offers enough tail recursion to handle complex cases though they both offer simple support.

As your own link makes clear, Scala does not have real tail recursion because of the JVM. It has a very limited form of tail recursion.