Super disagree with this theory, at least from my own perspective. I've been working for the last 25 years in various environments and I've never once even considered leaving due to anyone (high-performing or not) leaving. I think there's more factors to consider with something like this. If you're someone whos flakey, or just doesnt need your job, I would imagine you have a higher chance of leaving a job for a trivial reason. I'm like a oak tree, I don't quit jobs.
As a person whos been in retail for 13 years, my guess would be that its almost always more costly to deal with shoplifting than let it happen. Especially if you work somewhere like Dollar Tree or Walmart or Big Lots. Places like these pay very little per product on the shelf, depending what it is. And theft can be written off at the end of the year, if I'm not mistaken. So the choice is, let them steal, write it off, and hope no one gets hurt. Or pay security to be there everyday and buy special security equipment to sound off alarms. Not to mention remodeling your store to accomodate security measures.