Shouts cover the entire map.
People generally don't use Yell instead of Shout unless they're trying to get more attention with brighter text, or specifically trying to not bug the entire zone with it.

Shouts are in orange.
Yells are in yellow.
Say is in white, as you've seen.
(You can change the colors if you want through Character Configuration.)

As Sagittarian said, there's usually not much Shout chatter until you reach Mor Dhona, since that's a common place for various endgame matters. Outside of there, people are usually just quietly crafting or leveling and don't have much reason to stay long.