The parents could also check their kids phones and ground them if they find them using social networks.
The parents don't actually need their adult, childless neighbors to show their IDs to protect their kids, but it seems we're going down that exact path.
Needing to have an attested device made by one of two US companies and not even rooted, just to watch a true crime podcast on youtube.
Also, while very hard to implement today, when most people have their digital IDs on their phones, implementing a "real name online" policy will be easy, one software upgrade and you'll need to provide your real identity to every social network or website.
The parents don't actually need their adult, childless neighbors to show their IDs to protect their kids, but it seems we're going down that exact path.