I agree with most of what was said here but I think there is also a societal problem in the mix. A sizable chunk of us live away from an extended family network.
Institutions that would have traditionally helped families along have now become quite scary leaving parents isolated and without much back up.
Church and their child sex abuse scandals - means that most parents will not trust them
Scouts - ditto
Police - too many scandals involving cover ups, sex abuse scandals, corruption, rape, even murder. Also, little emphasis on crime prevention, massive resources given to crime solving. We need more bobbys on patrol etc.
Schools - focus on the wrong things! LGBTQ2Spirit /kind /empathy and so on rather than a tight ship with discipline. When my dc was bullied the school immediately jumped to a binary position - the victim as vulnerable and meek - she was not / the bully as a victim of violence - he was not. So, they moved my dc to a "safer" class but left the bully with his pals; took my dc to chats on "how to speak up" but the bully had no intervention and so on. Really ridiculous.
Modern psychology plays a large part in that kind of framing, along with the idea that almost everything is trauma related or inducing, and most have some disability/disfunction. With this belief system, we wipe out resilience, self decline and self esteem.
Prevalence of, or perceived prevalence of child sex predation. In which case the sane option is to keep them indoors.
I agree entirely that parents need to be able to say 'no" and actually do the hard work. But I also think the deck is somewhat stacked against them.