I'm really curious about this as have never thought about it much before and am now seriously second-guessing myself!
My 2-year-old DD falls asleep between 7.30 and 8 almost every night and tends to sleep well through the night. We have a consistent bedtime routine. However, occasionally - I'd say once every 2 months for the past year - she stays up late to 10/10.30ish. This is always in the context of a family member having a birthday party and wanting to go out for an evening meal or to have guests round to theirs. DD is the only kid in the family. Invitations always make it clear that she is welcome and so rather than getting a baby sitter, I always bring her along. She is used to restaurants; doesn't tend to eat much that late and always has dinner before we leave but is easily entertained at the table by drawing or chatting. If we go back to someone's house instead, someone is always playing with her. Me or my DH might have a couple of drinks whilst the other stays sober to be lead 'parent on duty' and drive us home. Afterwards she falls asleep in the car on the way back, gets carried up to bed and sleeps well. She has dropped her daytime naps usually but will have one the next day if we've been out late.
Anyway, when I was out with her at a restaurant last night, a stranger asked me why my toddler was out so late in quite a critical way. It was nothing to do with her behaviour - she was really good and quiet in the restaurant, not bothering anyone that I can possibly discern. But it made me think: is it somehow cruel or abusive to do what I'm doing?
I come from a background where kids being treated in quite an adult way and being part of adult events is quite normal so perhaps this has skewed my thinking on this.