While I am a peace-loving, Pollyanna, give-everyone-the-benefit-of-the-doubt type of girl, I think that people who habitually and purposely steal other peoples' lunches in the work place are bad bad people.
Seriously, and I am not talking about, "starving, come in off the street, just need something to eat." I'm talking about the kind of sociopath who has a job, money, and a lunch hour where they could go purchase their own food, or order take out, and yet, there they are, stalking through the lunches of their coworkers, stealing food for the sheer thrill of doing so. These people are untrustworthy douchebags and should be shunned from society.
I mean, what has to be going through their heads? They work with their victims. They are committing their crime in a public area. People look forward to lunch. They know what they brought to eat. It is just unconscionable.
The best (and most logical) punishment, in my estimation, is a Lord of the Flies/ LOST sort of scenario in which discovered lunch thieves are placed on a desert island and all forced to make elaborate, delicious lunches each day, which they then put in a refrigerator that is routinely raided by crazed monkeys or possibly genetically-engineered dinosaurs, leaving them having to eat grubs and coconut milk for eternity.
They should also be fired.