Unionised crew spend twice as long per layover tthan EK crew, requiring twice as many bodies and doubling the salary, allowances, and hotel costs
Layover times have nothing to do with unions. The fact remains that EK is ultimately the government and essentially there are no laws so therefore the minimum rest is whatever Emirates says it is. Just like your work contract. You sign a contract but don't expect them to honour it.
Same as with factored flight time. Every airline in the world logs flight time as flight time but not at Emirates. You can fly for 15 hours but only half goes in the logbook.
I believe the FAA were looking into some of these issues but not sure what came of it.
Pretty hard to compete with that sort of competitive advantage.