I work in a company that produces products in those plastic packages (referred to as Clamshell Packaging), and it definately done as a theft deterrant, especially on smaller and easy to pocket items. And, as much of a pain in the butt it is, it helps with loss prevention to the retaillers, which in turn keeps them from passing the losses on to the consumer (in theory ).

Theres a whole set of different pieces that go into a retaillers loss prevention/theft prevention program:

- Theres physical deterrents , such as clamshell and theft deterrent packaging, dye and alarm tags that can be removed by the retailler, as well as alarm sticker tags (the two main vendors are Sensormatic and Checkpoint) - ever notice those stickers on the inside of boxes? Those are deactivated when the item is passed over the deactivation pad near the till (the one that normally says 'dont put your credit cards here'). Have you ever gone through the doors to a store and set of the alarm on the way in? Its possible that something you have on you has an active antitheft sticker still on it.

- Theres surveillance equipment and staff - CCTV systems, video recorders, etc. that are monitoring both the customers and the store staff in many locations. This helps to reduce both internal and external theft, works as a deterrent, and can be provided as evidence. Theres often plain clothes security staff patrolling larger stores like walmart, etc. watching the customers to see if anyone is trying anything underhanded.

- Theres transaction monitoring - this is where the transaction data from all registers and all stores that has taken place during the day is taken back to a centralized location, and processed into a database (this is common with larger retaillers). Now, certain trends are monitored, such as multiple returns to the same credit card (customer theft attempts of stolen items), multiple returns using the same receipt numbers, multiple returns by a single cashier for cash with no receipts (internal theft prevention), and the list goes on and on.

These are only a part of the things that retaillers do to help with a loss prevention strategy.

And on a side note, yes i totally agree that those darn clamshell packages are a right pain in the rear to open. One of the tricks is to get a pair of scissors, open them and use one blade to slice down beside the seams on the back of the package (the back of the package is almost always the flat part of the package, where the front is usually bubbled up) - top and sides - which usually allows you to open the entire back flap off the package and get at the goods.