Worldwide Flights Why Do Airlines From The US Always Say "heavy" After Their Flight#, On Each Worldwide Airport?

Why do airlines from the US always say "heavy" after their flight#, on each worldwide airport? - worldwide flights

I live in Europe, and there is a change of grave ATC Lufthansa plane to another, right on the first call, they say hard, and then never again .... But the Americans always say after each survey .... Why?