In Thailand there is a bow culture and it is still in practice today and how low you bow depends on the status of a person you bow to. If it is a King you would literally bow to the ground as if you are a slave and not a person. You also bow very low for monks. For parents there has to be respect and of course a bow but not as it is to other elder citizens out there. 

Personally, I dislike this because most people fake it. Who does that out of love and true respect? It is a learned behavior in life and you just apply it.