Regarding digital copies, just a thought, and I have no idea how you'd implement it, but you could upload them all on the site and somehow the person gets a code and inputs it into the site, and it comes up. Like I said, no idea how you'd implement that, maybe something to do with the tickets, but yeah, then you can't get hold of another persons picture. You could charge a small fee to cover extra staffing costs. Personally, it doesn't bother me, my photos have always got back fine, but last year I had my Christopher Lloyd picture and I had run out of cash and my card had been put on hold, and it was only because the very kind man at a stall gave me a free photo wallet that it got back home safely. It'd have been nice to just have that bit of security that even if my copy was damaged I still had the online one. If I had to pick between only having either a physical copy of digital copy, I'd definitely choose physical though.
But I know it's not like you're trying to do this, there just isn't a viable way to do this. Which kind of makes all of this what I just typed irrelevant, haha.