Well, some of their chief competitors (i.e. Ariane 5) don't even do a controlled re-entry of their upper stages, so they don't issue warnings at all. They reenter anywhere on the planet at an unannounced random time and place. In a sense SpaceX is a victim of its own success here.

Falcon 9 destroys its upper stages in a controlled manner, in a deliberately chosen re-entry zone (sparsely populated ocean). Ariane 5's cryogenic upper stage can't do this: it's a liquid-hydrogen engine without a relight ability—after it turns off once, you can't reignite it a second time (for a re-entry targeting burn).