Was just in Cambodia.

IMHO, as in China, tipping is something imported by foreign tourists and which is not part of the native scene.

Nonetheless, some tourists cannot control themselves in their imported desire to tip where it is inappropriate.

PS I am still laughing about the clipboarded list on the counter, at the immigration crossing from Thailand, where you could sign-up to give 100 Baht in explicitly stated (in English) "tea money" to the thuggish looking Cambodian authorities.

Bad enough to give the corrupt government twenty bucks cash for the visa.