mkdir -pv not verbose

Macs use BSD-based code that is (mostly) POSIX compliant but (mostly) without GNU extensions (such as double-dash long options). The man page does document -v and -p, and -p works but does seem to suppress the -v option (which is probably when it is most useful).

One of your options is to file a bug with the Darwin or BSD teams, or with Apple. That's the way it is; it is arguably not the way it should be. (GNU mkdir supports -v and prints the directories it creates when used with -p, which makes more sense, and supports the 'it is a bug' contention.)

With thanks to SnoringFrog:

Another option is to install and use the GNU mkdir command on OSX. It is part of GNU coreutils and you could install it as explained in How to replace Mac OS X utilities with GNU core utilities at Ask Different. Then, you could alias mkdir to point to gmkdir to get the expected behavior (assuming you don't use --default-names when installing the GNU tools).