I have always considered a (the?) major difference between the US teams and others that rank high in the worlds is team flying being allowed in contests in other parts of the world. While our (US) pilots team fly in the worlds, it's hard to beat a pair that has been doing it all the time for a decade.
A parallel is working in the shop with a person all the time. We sorta keep an eye out on the other and can anticipate what they need/want before they ask. Outsiders see a lot of work getting done with little conversation that is related to the work.

A bit lower on the "difference list" is the state support for soaring in some countries followed by the way some countries pursue training/mentorship in XC and contest flying. The support would also include the amount of time pilots can afford to fly. Seat time is hard to beat but I feel team flying makes more of a difference at the level of the worlds.

I don't think the types of tasks we fly in contests is as much of an issue (as what I listed above) regardless of what some may "discuss" in various places.

The US has fielded some good teams but I'm on the fence about allowing team flying in our contests. While it will help in the worlds, our large geography may skew US contest results if some teams can make it while others can't.