Colour highlighting was intentionally removed when ncal is invoked as cal, as per https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=904839 cal being there only for historical purposes to give the old style output and with the same API (see also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=867995)
I agree the man page could be improved to make it clear highlighting is not enabled when invoked as cal or that ncal should be the preferred command. When invoked as ncal, the current day is highlighted, and you can use ncal -C to get the same layout as with cal and highlighting. See also GNU cal (gcal) which highlights the current day and has many (insanely) more features (the one I use personally is gcal .. or gcal .+ to get a three month calendar; similar to ncal -bB1 -A1 and ncal -bA2 respectively). Its output is similar to that of ncal -b with Monday first as is more natural in most parts of the world. -- Stephane
