There's createdb from memory (?), but for other bits and pieces, it might be worth spending a bit of time on a thin wrapper script e.g. "create-pg-user foo" that just wraps the annoying parts, but using your environment specific bits and pieces if needed, or using a C/Python/Ruby/Java/etc api. At a bit of a different level maybe some Ansible playbooks that hide away the psql level stuff, so they can be reused.

I fully agree though and in thinking about it, a range of CLI level tools would be nice. I guess then the team would have to play catch up with any syntax/api changes for those tools too, so its adding that annoying extra bit (albeit fairly small probably). But I guess its the annoying extra bit getting down in one place, and not hand-crafted by everyone.