I think the key here is non-technical users. I know many users who have fairly recent Mac hardware that stayed on Snow Leopard because of Rosetta. I cringe to

I think the key here is non-technical users. I know many users who have fairly recent Mac hardware that stayed on Snow Leopard because of Rosetta. I cringe to think how many similar users were affected by issues such as the recent Java browser vulnerabilities but no longer receive support for that version of OS X. In this case, OP mentioned Erik's did have an "IT" employee. I'm guessing the IT individual's knowledge did not extend to having dedicated POS machines or understanding the concept of user profiles and group policy/rights. With cloud-based/hosted POS systems now, security concerns don't necessarily stop at one's browsing/computing platform.