Concerned Citizen wrote:
Airlines do not take charge of unaccompanied minors under any law that I know of. If you know of one, please cite it.
Simply read the unaccompanied minor procedures for any major airlines. You will see many references to "custody", and "airline will be responsible", etc. Most airlines won't allow online booking of unaccompanied minors so they can force the in-person signing of custody and liability forms. Working in that industry, we go through a lot of work to keep track of minors and the primary reason is liability to the airline.
As far as liability waivers they are worthless if negligence can be proven or claimed. A waiver in a recreational activity is an acknowledgment by the participant that there are risks involved, not an OK to the organizer to ignore potentially unsafe conditions. The more complicated the logistics for an event the more opportunities for questions of liability.
Working with events I know there isn't some national "law" that says minors can't run marathons and I've never claimed there was. What I have said is that liability will govern the willingness of any event organizer to accept minors or any other class of participant. Did events allow minors in the past, sure, I'd be willing to bet that the reason that Chicago or New York added the restriction is either some parent made a stink or their carrier got nervous about some parent making a stink or said something like the price for coverage would go up if minors were allowed. Dollars to donuts if some 75 year old keels over and their family sues you'll start seeing age restrictions at the top end too.
Course logistics are very important in these liability decisions, and I've had carriers flat out say they won't offer insurance if certain types of participants are allowed (i.e. restrictions on roller bladers and wheelchairs in many events).
If Grandmas allows 12 year olds, great, go there to set age group records. They either haven't ever had an issue or have had the time to work things out with their insurance carrier. Having run the half and full there, and having a sister in law that lived a few miles from the start, I know there's not a whole heck of a lot in Two Harbors so the odds of misplacing the minor are pretty slim. You're also not hanging around for very long like Boston or New York.