`ls` seems to have changed (unless ls has distro specific arguments). When I use `ls -r` I get reverse order. To get sub-directories, I have to use `ls -R`. I'm running Mint.
I don't think it has changed. IIRC recursive in ls has always (in the near ΒΌ century I've been using Linux and occasionally other unix-a-likes) been specified with an upper-case R. I suspect an uncorrected typo.