Few people are as Machiavellian as I, but I wouldn't be overly worried about having someone snap a shot. Granted, I am extremely fast and hold advanced belts in 3 martial arts, so it'd be a bad move.
But that aside, you call out "Stop that guy's got my camera" and he's going to be facing 3 stroller moms, 2 dads on vacations, 20 CMs and at least a couple of hyperactive teens...not likely to get very far.
There are great stories in the Mouse Tales books about how far people get after commiting crimes...they don't. We're talking about a place that's as controlled as a Las Vegas casino.
That's no guarantee, but professionals will stick to picking pockets as opposed to a grab & dash - too many cameras for evidence and identification.