There is a culture in Malaysia and among Chinese in Asia: people will call an elder person either sister or brother, or aunt or uncle, depending on their relative ages. That is a manner or respect, even though they are not related.
It is a virtue that most Chinese are proud of; something parents begin to teach their kids when they start learning to talk. For example, the parents would teach the kids to call their friend Brother/Sister XX or Uncle/Aunty XX when they meet.
If the younger knows the elder’s name, the younger would take initiative to call the elder Brother/Sister XX or Uncle/Aunt XX instead of hi or hello.
And it is not very good manners to ask someone older what his/her name is at the first meeting.
A lot of times, you would hear someone call someone uncle or aunty in public like in a store.
In the USA, when two strangers first meet, they will tell each other their names or ask what your name is. And most, even when they know each other or are related, they just say hi or hello.