(the folks who steal or otherwise misappropriate TITOs almost always use their player's card befe or after the theft.) alternatively, they can pul up digitized video and retrace the person's steps and almost always can match the person with player's card data. and - once reported - the casino can usually check the surveillance video and can almost always make a visual ID and approach the person if still on property. I was a victim of TITO theft at mohegan and the casino made good on the lost money (around $140, if I remember correctly.) and i've read man stories online of people forgetting their TITOS or TITOS being snatched by 'surfers' or professional teams who distract players. IF they have been notified by that player of the loss in a timely manner.
and based on stories i have read online, casinos generally go to extraordinary lengths to return TITOs or funds associated with them to the rightful player.
The casino has no obligation to recover funds if it doesn't know any have gone missing, which is the case with most of these thefts.