The airport, Harry Reid international (<-, just for the lib haters) is a funny situation. Of course when it was built, it was just south of the southern most place on the strip. All the land south, towards South Point and to the east toward Henderson was just open space (except for Wayne Newtons spread a mile east, which at the time was in the middle of nowhere.) Now that area both south and east is all built up and if you look at a map of Metro Vegas the airport is right dab smack in the middle.
I am surprised at some point the didn't build a new airport further out, maybe down toward the M before that area started growing. But the powerful taxicab lobby group probably wouldn't have stood for it. They have a monopoly of getting people from the airport to the strip. Any further away and people might balk at the price.
Anyone who questions how powerful the taxicab lobby is, just go to the end of the monorail at the back of MGM about a 100 yards away from the corner of the airport property. It would have taken less than half a mile to extend the monorail to the airport terminal and transport people much more efficiently that 1000 taxicabs. Ever been to the airport on a Friday afternoon and evening and seen literally 500 taxicabs lined up? What a waste.