From: Northern Virginia, USA
When I was in the Army, I got to meet a group of WWII MPs who were at Fort Hood to check out their modern counterparts. They were quite surpised to see that MP teams were now armed with rifles (one w/grenade launcher) and driving around in a HMMV w/pintle mount machine gun. According to them, the only time they were issued rifles was on prisoner guard duty, and even then, they had very minimal training with them. Another thing was that most of them had medical problems that rendered them unfit for infantry assignments.
Also remember a lot of the transport troopers were black, and weren't trusted with weapons.
"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."
-- Thorin Oakenshield