My first thought was that I had missed that step in the initial installation, then I saw that I didn't have that file in 9.1.2....
I had noticed the USPS stuff and I remember seeing a post about it - was thinking "that was fast"! Then when I couldn't find anything in Admin - shipping, I figured as much!
Keep up the great work!
Hopefully, I'll have time to do some poking at the group membership functionality soon.