i agree that children should have regular and fairly early bed times. If you look at the sleep requirements for children, they are quite high, but I don't think the odd late night on a special visit/occasion is too much of a problem.
3 of my GC live in Spain and have a Spanish mother and they go to bed very late. To be fair it is incredibly hot in the summer. They phoned yesterday and said it was quite cool only 25+. It is usually 30+ to 40. The only time it is pleasant to be out and walking is early or late. They also eat late too. 8 pm or later. However, I have never understood why the don't change the routine in the winter.
2 GC in England go to bed between 7 -7.30. They are twins but one is an owl, usually not asleep before 9 and the other a lark.