I don't think it has changed. IIRC recursive in ls has always (in the near ¼ century I've been using Linux and occasionally other unix-a-likes) been specified w

I don't think it has changed. IIRC recursive in ls has always (in the near ¼ century I've been using Linux and occasionally other unix-a-likes) been specified with an upper-case R. I suspect an uncorrected typo.