Pavlov you haven't said how you live, but you have said your philosophy on how people should live in streets where houses are close together. People are entitled to respond by saying they couldn't live like that. I couldn't live in a street where everyone had your philosophy either, I would also have to move.
Why couldn't the kids have done their gig indoors? Then they could have still had their fun, but the impact of the noise levels would have been significantly reduced for neighbours.
Also, WRT prior notice not making any difference - of course it would have! Then the OP could have planned what time her guests were going to arrive, planned if necessary in advance to have dinner inside rather than outside, etc (this might necessitate a change in menu so prior notice essential), negotiated with next door saying "Ok, you were planning noise from 6-8, how about doing it from 5-7:30 instead, only we've got people coming round at half 7 and we were planning to eat in the garden" - prior notice gives you all those options and it surely just shows some respect?
I think if you choose to live in a built up area then you should accept that some noise may occasionally be heard, but equally if you choose to live in a built up area then you should show respect for those who you will be disturbing by doing everything you can to reduce the impact of your choices on them - by things like giving notice beforehand, doing really noisy things (like live bands FGS) indoors with the windows etc shut before perhaps then hanging out in the garden when the gig is over.
If you want to be able to live exactly as you want to, all the time, whether that is noise-free or noise-abundant, then perhaps buying a house in a built-up area isn't the best idea. However given that often that requires money we don't have, surely it is respectful to limit the impact of our behaviour on others in the meantime.
It's a bit like the arguments for why people should be allowed to smoke in pubs etc - smokers felt that not smoking intruded on their right to enjoy their evening as they wanted. The flip side though was that non smokers couldn't avoid the smoke of someone else's cigarette once it was lit without leaving - hence the ban.
It's the same thing and that's why, Pavlov, your argument about respect/tolerance on both sides doesn't hold up. It's NOT the same on both sides, because the people liking silence can't make themselves deaf for the duration of the noise. They have no choice but to listen to it. The people making the noise are always the one in control.
I do though think that essential noise like building works, with a finite beginning and end, are more acceptable than non-essential noise such as an outdoor gig where an indoor one could just as easily have been done.