It's a parallel fantasy world. Although the fantasy isn't very different from today's reality, maybe just maybe in this world of fantasy F-15 have somehow magically gotten the ability to land on the fantasy carriers.
Idk why you're taking this so seriously, mostly no one else cares much about whether the game has any relation to real world. They just want a good story, good graphics and good gameplay, to hell with the rest.
Mainly because the developers went to great lengths to claim how realistic they were making it. And the realism level is very close to 0%.
Ah... well that's a pretty good reason then. It would've been a totally different thing if credit had been(wrongly) given to them, but if they took credit where they shouldn't have, then they get what they deserve.