I personally think that the policy should be based on the age that adult tickets are required. Bottom line is if someone has to pay the adult price, they should be treated as an adult.
So I see two viable options, lower the minimum age to match the current ticket policy or raise the child ticket age limit to 13 and under.
I can honestly envision some lawsuits if they don't match. I don't know who would win, but they cost money to defend, which in turn raises prices for everyone.
I can also see some issues, say that a 13 year old is at
Disneyland with Mom and Dad. Mom decides to go DCA and Dad stays at DL. Now Dad has to leave to go to work, so the kid wants to join Mom, does that mean that Mom must now leave the park to come get the 13 year old, who is perfectly capable of switching parks?
Or what if this same group needs a locker and all of the lockers inside the parks are full (happens a lot during the summer). Now, lets say Mom and Dad have mobility issues or get hurt and are in first aid, but the kid needs to get something out of the locker. What happens in cases like this?
I can see this causing a lot more problems than just these. Additionally, I know many 14 year olds that shouldn't be left on their own and many 9 year olds tht would be perfectly fine.