The 'Arrow' example is probably not quite as simple as it appears to be.
We've been running a Jupiter video display processor in our NOC that pipes in a dozen or so vga sources and pipes them out in any sizes, config we choose to 6 outputs.
It runs win2k and has only been down once (unplanned) in the last 5 years and that was due to a generator issue.
While I worked hard to find a 24 X 7 X 365 solution running *nux there were simply no products on the market that met our requirements when we purchased it.
I would imagine that the airport uses a similar system for their signage.
I'm not saying that running windows for this sort of solution is ideal, only that (at least a few years ago) there was nothing else to choose from.
I'm hoping there will be something on the market when our solution reaches it's EOL soon.