Mmm, I've never seen a US military convoy try to get through a US city. I assume it must happen sometimes, but I've never seen it. The US army isn't given to convoying around as much as you'd think though. They have large bases, and mainly stick to them. They aren't going off to N. Dakota to fight insurgents, so our situations are a bit different.
I have *passed* US military convoys, out in the countryside. They tend to follow the law very exactly, and no one else drives the speed limit, so they are the slowest traffic. But @
Oscar has a point, most US bases are away from large cities, or the city exists almost solely because of the base. Or, in the case of San Diego, they have a chunk of the city to themselves (Coronado)
Google Maps
Naval bases are a bit less intrusive anyhow.
But to someone else's point, Americans do at times resent Presidential VIP treatment when it blocks roads. It tends to come out from people who already don't like whoever is president at the moment, or if there is some really dumbass thing going on - Bill Clinton was ripped pretty good for getting a haircut on Airforce One while on the runway, holding up other aircraft. (The story is disputed, but people have been bothered by Presidents). Lesser VIPs get little to no tolerance for prima donna behavior here. Hollywood uses the trope to show that a character is an ***, not that he's important.