Who are you to say it's 'absolute nonsense'? Perhaps you just haven't witnessed much of it personally.
I like children and I do think the majority are still well behaved, but this thread isn't about them, it's about the ones whose parents allow them to be feral because 'kids will be kids' and should apparently come first at all times, even when it's at the expense of other people. Children being allowed to have and do every single thing they want regardless of whether it's actually in the child's interests, 'no' not being in the parents' vocabulary, you're seriously saying you don't see this? Or see that there's more of it than there used to be?
Things like kids running round the tables in restaurants tripping up the wait staff, or screaming like they're being murdered in their gardens (I don't mean the occasional scream as a normal part of having fun btw, I mean that awful sustained din some of them seem to enjoy producing) have always gone on to some extent, yes - but at one time they were the exception rather than the rule. Admittedly stuff like having iPads blaring in public places without headphones is a relatively new one, but are you really fine and dandy with it disrupting your meal when you eat out? Parents did used to have a better grip on how to be strict when it was needed (I don't mean hitting them btw) and actually teaching kids how to behave in situations where other people's comfort has to be taken into account as well as their own.
I do think it's true to say every generation thinks kids' behaviour has gone to pot, but the difference nowadays is that with some kids today it really has. And actually I do feel that society, while not collapsing, is in a bad place because of excessively permissive parenting. What's going to happen when children who have grown up with no boundaries have to function as adults?
Given that you've stated your age, I'm going to hazard a guess that you know full well all these behaviours are worse now. You just don't want to admit it.