Back in the day, parents who would not risk leaving their kids at a playground (like, ever) would let them hang out at a library. There are a ton of children's books that are older than I am that describe in loving detail the relationships that developed between librarians and children who were not with caregivers. Librarians, in practice, are not so enamored of this, at least not today. A few years ago, I watched Mayberry's (<-- not its real name) town library wrestle with the unattended child policy.
So what do these policies look like and how common are they?
That's about what I would want the policy to be. Your illegal, underage babysitter and/or sibling can be there with a younger kid as long as the sitter has ID and is at least 14.
Michigan sounds downright cruel, potentially!
"A child or group of children who have been warned of disruptive behavior and/or excessive noise, and continue to exhibit the behavior will be asked to leave the facility." The rest of the text suggests that they aren't talking about 7 and unders here, but it seems at least possible that Clare's library would just boot a bunch of 8 year olds for being rowdy, and if there were no parents to pick them up they'd be on their own.
Idaho, land of libertarians, has this to say:
Don't drop your 10 and unders off and expect us to take care of them! Also, pedophiles! The usual caregiver can be as young as 14 rule.
Time limits appear to be another way to deal with the we aren't your babysitter! problem. No cell phone use in library and no public phone -- I understand why, but yikes. This is what librarians struggle with when local parenting standards do not involve hiring caregivers for one's own children beyond the age of 8.
Aurora, CO seems to understand there might be relevant labor law; they require 16 year old caregivers, "with no exceptions".
Unlike Clare, they have a plan for what will happen to disruptive youth that doesn't involve booting them out the door unattended.:
"Disruptive children, attended or unattended may be asked to leave the library after one warning. In such instances, parents will be contacted or, if the parent is unavailable, police custody will be utilized."
In case you didn't grasp the implications:
"If a child age 15 and under is left unattended at the time of closing and attempts to reach the parents have failed, the North Aurora Police Department will be called to take responsibility for the child."
If you don't have your own car at closing time, we're calling the cops. I'm betting this is because of dangerous roads/climate and a total lack of useful public transportation.
Here's a shocker: "Children up to age 10 must have a parent/caregiver in the immediate vicinity of, and in visual contact with them. The assigned caregiver must be a responsible person and must carry emergency contact information. ... [standard exception for kids at the puppet show or other program while parent finds a mystery to read] ... If the parent/caregiver cannot be found, or if the child is found unattended again, the Sheriff’s department will be called for assistance."
VISUAL CONTACT! IN A LIBRARY! FOR 9 YEAR OLDS!
If you are in Massachusetts or the PacNW or a rich area near DC, or the Bay Area or whatever, you very rarely see unattended children. They go from attended in strollers to attended in play spaces (public or otherwise) to attended in parks and playgrounds to structured sports and other activities. Everyone is well-behaved and the caregiver rushes over apologetically whenever the little one kicks sand in someone's face. In this environment, a hypothetical unattended kid seems like not too much of a problem. The other caregivers can gang up on any troublemaker and deal with it or just remove their own charges from the scene.
But if you are in Idaho or Colorado or Michigan or Louisiana and a whole lot of kids are unattended, parks and playgrounds look kinda dangerous and dropping the kiddo off at the library for a couple hours after school or maybe all day on a holiday or whatever might seem like a safe child care solution when you cannot afford something else -- or they cancel due to illness. And the librarians of Idaho and Colorado and Michigan and Louisiana are unamused.
Reason picked public parks for a reason, I think. The law on leaving kids unattended in homes is pretty sparse (guidelines only) and libertarians like it that way. Obvs, a libertarian isn't going to want unattended kids running around in backyards other than their own (another thing that was common Back In the Day); advocating for unattended children At Large would inhibit the right to Shoot On Sight in response to trespass. Stand your ground/the Castle doctrine is already in enough trouble. There's no way it would survive this argument: "It was posted No Trespassing!" "The child you shot can't read/wasn't tall enough to see the posting." Private businesses can decide who they want to serve or not serve -- libertarians aren't going to mess that up. Unattended kids in the street (another public space) is an interesting question, but I think the I Want To Drive Fast Through Residential Areas rule beat the Let Parents Decide What Their Kids Can and Cannot Do rule. If kids can legitimately play in quiet streets then safe speed will inevitably reduce, and libertarians Do Not Like (I say this with confidence, because I've heard them on the subject enough times and read them even more).
I'm not sure what's left other than public parks.
I may or may not add to this. I would vastly prefer to go digging around in radar signal processing.