I have NO idea! But I agree with you, it makes no sense to me either. Plus, I don't understand why they can't give the guest the ability to designate what ticket to use when, if they are going to have a system that can't figure it out based on age, or some other obvious method that is stated so everyone knows before hand what ticket will be used automatically. There should be something on there that clearly shows the guest what ticket is primary. How else do they know?
I got so very annoyed with both them and myself on our last trip. It was my fault for not handling the ticket and moving it myself and avoiding putting myself in the situation where I had to get it fixed but if they didn't have such an idiotic system in the first place I would have never had to deal with it period. In our case, we have AP which expire between 2 trips and I wasn't sure when I planned to renew the AP during trip 1 or when we returned for trip 2, since both were in our renewal window, it depended on how much we spent on trip 1. I had to use some tickets I was using for someone else for future trips and just used those to book FP for the 2nd trip, just until we got our AP renewed. If I moved the tickets out of our names I got an alert from MDE that we needed tickets for trip 2 or it was going to cancel the FP. So I moved the out of our names until I got those messages and then would move them back to our names until we got ready to enter the park that day, until I forgot that one last day, when it did use a ticket entitlement instead of our AP. Which is frankly asinine. As I told the CM when we went to fix it, but in a nicer way. I said that y'all do realize that no guest would ever realize that they should even have to be concerned about what ticket is being used when and that an AP should always be priority over a ticket. Then that CM actually tried to look me in the face and say, with a straight face, that there would be a time when someone with an AP would rather use a ticket instead of their AP when they entered the park!!!!! I was so annoyed that I had to spend over an hour of what should have been our pool time dealing with fixing a problem that shouldn't even exist in the first place.
On top of that, I had to explain several times that just getting a single day ticket back wasn't sufficient, that I needed the entire ticket back because I needed to reassign these tickets to the correct guest, that these tickets were not going to ever actually be used by DH and I, how we only had them in our names until we renewed our AP. She finally got it, and did reissue the original ticket and all is good but wow, was it a mess that should have never been.