My niece and nephew don't call me auntie, they call me by my first name - I know they love and respect me though. So it'd feel very weird if other kids called me auntie.
One of my friends, now 40, was brought up to think it was impolite to call adults by their first names, and called everyone auntie and uncle. She has been with her dp for over 10 years and is literally incapable of calling his parents by their first names. She can't make herself do it - she says it just feels too wrong. But she doesn't want to call them mum and dad, as she's got some of those already. So she calls them nothing. His parents know this and find it amusing, but it's actually a bit stressful for her. Last birthday her card from them was signed 'from the people with no name'!