The US system doesn’t seem less "advanced" to me. It cuts down on the number of people that connect through the US on non-US itineraries, but I don’t know that there are many US hubs agitating to become city-sized duty free malls like Dubai, Frankfurt, etc. And it makes our airport layouts much less complex.

There are almost no routes that would want to use the US as a midpoint due to geography. It's pretty much only routes to Central America that make any sense, and there's just not a lot of them.

So the US never felt the need to build airports with dedicated international zones.