Man that meme really went wild huh
Yes, CPS in one state did something ambiguous and alarming to self-proclaimed "free range" parents.
No, you probably don't have the full story that a guy who had never seen the children before was concerned about their safety in that part of town, he decided to call 911 instead of talking to the kids and coming off as a creep.
Yes, that one town's police department did get the CPS' attention, and the CPS did an investigation and found something arbitrary which is rightfully concerning.
No, this isn't indicative of the entire US culture or widespread neighborly paranoia about children walking unattended.