Traveller is Feudal Europe. Corporations are the new Robber Barons and Nobility, the Imperium is the Holy Roman Empire. It holds the space in-between powerful corps and factions, and protects the 'necessary' lines of communication, supply, and armament throughout the territory. Everywhere else would be solid bedlam. He with the biggest guns is lord of all he sees and can shoot reasonably well at.
Makes me think this applies very well: "You can get more done with a kind word and a gun, than you can with just a kind word." The Corps do maintain a Rule of Law, is it moral or ethical? Probably not, but it is stable, like a mafia-induced stability. As long as you don't cross the corps and their puppet political authorities, and pay the random, abusively high, and constant tolls through their space, you'll travel safe and well.
In RL corps can have mercenaries, but most police departments aren't on the take. They can just rob you on their own with Civil Asset Forfeiture, they don't need buyoffs from corporate lords. So I would argue that the Traveller setting while technologically superior is politically inferior. Why? Because civilizations are prone to collapse and Traveller has been filled with empires/civilizations collapsing right?
Given that the US is an oddity for having peaceful transitions of power for 200 years and you put that on a galatic-scale. In setting, we should be proud we made it back to Feudalism or have been there for at least 800 years. Technology reduces the damage of distance in stability of ruling, but Traveller has a hard barrier to make Rule of Law harder. There isn't instant communication (going back to my pointing out of the Physics "No-Clone Law") so "Rule of Law" only exists where the Empire or local lords have forces. Imagine an America with police but without telephones, no radios, just a pony express to deliver missives. Don't tell me you wouldn't expect vicious exploitation in the gap of communication there. That was the Wild West and the Frontier for a long time. That's why the Mormons got so messed up and why slaves could maneuver out of the South before the Civil War. Now we have near instant communication and while crimes may occur in "patrolled-light" districts, most areas have minimal crime.
The British fought wars over slivers of land to improve communication, aka Yemen, Singapore, Hong Kong, the occupation and annexation of Egypt, the occupation of Gibraltar and Malta, etc.
Interesting to see the initial remarks on trucking though. Merging the two takes me to the place of Fast and the Furious though, more than RL. That movie series features many trucks being hijacked, drivers murdered, and cargo stolen than occurs in RL.