@dprapr: today's youth is mainly spoiled and if the mule doesn't get what it wants right away, it's already crazy.
Please, that's the expert opinion today! A parent who wants to raise their child differently, with some restrictions, so not everything is brought to their ass, into a capable, adult person who won't need mommy and daddy until middle age, is a bad parent! Neglects the child!
I read online a mom's confession: at the first parent-teacher meeting, the teacher already hammered into their heads that they should do homework with the children, study with them, check if all duties are done... Please! Where is independence here, if the parent hangs over their head the whole school and if teachers and experts even promote it.
Then they have to make e.g. a poster. Most of course get help from parents (or parents make them themselves) and they have super duper products. Making posters is parents' task? Yeah and the one who doesn't, automatically comes out worse, even though their product is much more valuable if they made it themselves.
And of course we don't talk about parents raising super kids who must never experience defeat and never learn anything from experiences. Then we wonder how much crime, drugs, suicides there are among youth...
As for greeting itself: I also have various experiences. Yeah, I won't say kids can be much friendlier than adults and rarely is a kid as rude and impolite as many adults can be and if it is, it obviously sees a bright example in the family.
On the other hand, where has basic politeness gone? While with adults, say in our block, we mostly greet each other even if not with some - they know why themselves - very very rarely does a kid greet you. When we were little we always greeted. Even when we were still in LJ, before we moved to the village (where everyone greeted anyway, at least back then). They always told us at school and home that you have to greet.
What about today? Practically no kid greets you on the stairs or in front of the block. Rare exceptions.
I heard from a colleague that his daughter was somewhere in Croatia on school trip in nature, together with some group of Croatian kids. Croatian kids greeted their teachers when they met them, Slovenian ones didn't!