I wonder if this is an operating system, or what a laymen would potentially call an operating system, maybe some sort of full screen application. I would guess the latter.
* it's a complicated vertical market with buckets of cash
* there are two main providers, Landmark and Schlumberger
* you buy most of your stuff from one or the other
* the software, at $10k/seat/year, is the second cheapest part, the cheapest being the beefy box with top-of-the-line 3D graphics to run it on. the highly-paid geologist or petrochemist or whatever to sit there running it is the third-cheapest part.
* the software is unbelievably shoddy for how much money goes into it. X applications in 2004 that would refuse to run in 24-bit, demanding you restart in 8-bit, that sort of thing. Hence my rule of thumb that "software quality is inversely proportional to ticket price."
* OH MY GOD THERE IS SO MUCH MONEY SLOSHING AROUND. So it was nice to sysadmin somewhere that would just spend money to do stuff properly.
* I daily wanted to stab FlexLM in the face. And it's the least-worst option on dongleware.
So maintaining their own complicated system of stuff that runs on Windows 7 is already what they do, and is relatively cheap compared to how much money is in the vertical.