Obviously, there are different laws for different states and yes--you're right that it's much more widely accepted, particularly out in the (wild, wild) west, but I'm speaking purely on a "was the gun actually registered in his name" matter? Judging by the state laws of Missouri, he either didn't need such credentials, or he had already obtained them. I'm guessing it's the former.
From the sound of your post, it came across as though you were claiming that you didn't need to have the weapon properly registered or have a permit to own it, and that any idiot could simply choose to ride around with a loaded handgun under their seat. That is obviously not the case. Many places require the weapon to be issued in someone's name, with something of a background check needing to be passed to get the weapon registered. As you mentioned, there are laws in some areas which require the clip/ammo to be securely locked up in one area of the vehicle, while the unloaded weapon is secured in another area.
Since the DA from the show-me state didn't see anything at all wrong with it, I'm guessing that they are somewhat lax on their handgun laws. Either way, Richardson should at least be required to give more drug tests from the NFL, but he likely would just claim that it was his friend's weed, and that he was an innocent bystander.
