"A proposition is objective if its truth value is independent of the person uttering it."
It is completely subjective when I decided that it was ok for my son to cross the street.
One parent may say their 5 year old can cross the street. Another parent may say that a kid has to wait until they are 8. A third parent may not decide on a strict age and go by when they feel that child is mature enough.
Parental rules are as subjective as it gets.
Most parenting rules are subjective.
Even in your weak point about red lights, that is still subjective. There are towns that have eliminated the use of red lights. So once again, a red light law is subjective.
https://www.dailymail.co.uk/news/article-1028740/Accident-free-zone-The-German-town-scrapped-traffic-lights-road-signs.html