Although I don't know their methods, they can save time by photographing the whole family and linking the tickets. Families usually travel together as a group.
They can avoid photographing kids since I don't expect the sharing of child tickets to be the problem as long as they are with the adults.
If the tickets are bought at the ticket booths, they should consider a quick photograph there. Maybe they should redesign the ticket booths to accomodate the taking of photographs.
Never get in line behind grandparents with lots of grandkids . Bad idea.
I'd never buy one, but if there are several companies doing it, then it must be a pretty big market for it.
Simple, but effective!
I would also add that passholders should be able to scan their own tickets. They should use that automated scanner where you insert your pass into like they do for all tickets at WDW. Yes, it's there at the DLR and works they just don't use it. And I'll add that one cast member should be able to man two turnstiles since all they'll be doing is looking at photos that pop up on the screens. That would save on labor costs which I'm sure would excite someone in management.