Anyone who does not have an ID will not be allowed on the tour no matter your age. When we took it there was a family of 4 who forgot their ID's or thought the resort ID was enough. They were not able to go on our tour.
I booked a Epcot tour last week and they were very clear that an ID was a must.
I think there are only 2 tours that allow under 16, the Family Magic Tour and The WDW Trains tour.
Bev