You've done a good job answering the question asked of me -- thank you. To add a little more, in places where security really matters, like DoD manufacturing a

You've done a good job answering the question asked of me -- thank you. To add a little more, in places where security really matters, like DoD manufacturing areas, there is literally physical security segregating everything from the people to the network to the hardware to the data from the unclassified parts. Knowing you could go to jail for a very long time if you do something stupid or illegal is a strong motivator. For those not so motivated, most places not only segregate the network but also the data: tapes or backup data are kept onsite in a secure area, computers used for interacting with the data never leave the secure area and have been modified not to have USB headers or removable hard drives, cables and gear are physically protected from tampering, etc. None of this is to say that all risk is eliminated, but since most systems are compromised by casual hackers using simple tools, adding the security you can is usually a sensible thing to do.