In other words, their net income is down. I wouldn't be surprised at all if the net increase in sales isn't just a temporary scramble to keep income up / items actually being rung up. The truth is this benefit will almost certainly decrease as more knowledgeable and productive servers find jobs elsewhere or find new methods around the system while the remaining lower skilled / productive settle in at the amount their effort is actually worth.

I have doubts this action would produce a net benefit in the long run. (As quality of service decreases.) Its easy to think that the only people stealing are the "lazy and incompetent". In my experience the most skilled "thieves" are also the hardest workers with the most in depth knowledge of the controls the restaurant has in place. They also tend to desire/need/feel they deserve the cash more than the average employee. (and to most extents all three are true) Of course, all of this applies to the tipped employees, non-tipped employees will feel this doubly so though their forms of theft tend to be easier to track / reduce.

Theft in a restaurant setting is a complex issue, there is no magic bullet to stopping it.