What? Those engineers are not badly paid.. Assuming the scientists' salaries also include their research funds (since researching costs nothing), the engineers are the best paid of the bunch, since it does cost something to produce items, so we can only assume that 100% of the money paid for engineers goes to them.
And they're building the stuff that will enable the planet to be saved, in perfectly safe conditions (ever seen an engineer die? (unless you play Redux!). That they would go on strike would irritate me to no end. And then what? After the strike you pay your engineers 10% more? Do you have to negotiate with them?
Having them not work at night is a nice idea, but rather pointless. To make everything scale the same, they'd have to work twice as much during the day, and events in XCom are separated by multiple days, so the overall effect would be small, if not negligible.
What about soldiers? They have the worst of it: Smallest pay and high casualties.. Actually, a "fatigue" idea that diminishes abilities (especially bravery) unless you send them to R&R would be a lot more interesting in the simulation idea.
