They're four Americans who would of missed their flight back to the states. Don't you think that would of alarmed friends and families to send help to find them? Four white middle class Americans missing in Mexico would be all over the U.S news. I think if they could of held on another day or so there would of been a higher chance they would of been found and saved by search and rescue.
I'm sure there would be an investigation, but it would take a while. Friends and family can call asking for help, but it won't arrive right away. They probably wouldn't have made it even if they held out for another day or two.
P.S. I wouldn't have said anything, but you did it six times in one post. It's "have," not "of."
Would have, could have, should have. There is no such thing as would of, could of, or should of.