system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar] Where are the water and earth shamens?

We know that the Air Nomad monks are responsible for identifying the Avatar when the rebirth cycle is on air. We know that the Fire Shamans are responsible for identifying Avatar's when the cycle is on fire and that they're supposed to be helpful and loyal to the Avatar, no matter which nation they're born into. Yet, when Aang travels to the Water Tribes and Earth Kingdom, he never even considers tracking down their Avatar temples.

This is especially strange since the Water Tribes should be on call to try to find the next Avatar after Aang went missing. 

What's up with that?
gpt
The four nations are each culturally distinct. While the Avatar plays a role in every nation's spirituality, how that manifests is different for each group.

In the hundred years war the Water Tribe has sort of drifted away from their spirituality. They maintain traditions, but mostly for traditions' own sake. Not that the people aren't strong spiritually, just that their society has shifted. (This is a plot point addressed in Legend of Korra)

The Earth Kingdom is huge, and has many culturally distinct states. If the Avatar was born there it would be up to local authority figures to put the pieces together. Kyoshi's Avatar-hood wasn't discovered until she was 16. That's probably fairly common among Earth Kingdom born Avatars. In Ba Sing Se, the institution that would take on that role is the Dai Li. (So, not exactly helpful to Aang)

There are temples to the Avatar all over the world. Visiting them each individually doesn't really serve much purpose to the Gaangs' larger goals. There's also something to be said for subtlety; Sozin ordered a genocide of the Air Nomads to wipe out the Avatar. Azulon did the same thing to the Southern water tribe. The idea of Aang showing up was so inconceivable that Ozai used finding the Avatar as a way to banish his son. At what point do the organizations whose sole role it was to find or serve the Avatar just disband?