Ok - it's not nice to laugh at someone at their expense. Really. It IS human nature to do so, though, and sometimes it seems like it can't be helped. But since all of us have been given more or less some sense of self control, I suggest you exercise it as often as you can - especially on an airplane, especially in the presence of those people for whom it's a mighty struggle to get the peanut package open.
There are seventeen peanuts artistically splayed out in and in front of the open peanut package here on the homepage of the Southwest blog. You can bet that great lengths were taken to place those peanuts just so for the photo shoot - the spacing is precise, there's a good mixture of whole and half nuts, and shadows from the perfect lighting fall gently around them. But wouldn't you have liked to have been in the studio when that package was opened? Does it look like they got it on the first try?
I've seen some amazing contortions in airplane seats after the Flight Attendants make their way through the cabin with snacks. Elbows extended, backs twisting, lips curving into a grimace; teeth, fingernails, paperclips, the ends of pens - all have been employed to try to get into what sometimes seems like and indestructible little bag. It can seriously crack the demeanor of the coolest, best dressed, most perfectly coifed flyer. Maybe you've been there yourself. If not, and this is happening with your seatmate, or the person across the aisle, the temptation to point and laugh may feel overwhelming. But, remember your self control...and as gently as you're able to, point out the tiny little tear on the right side of the package that's there to serve as a starting point for peanut access. (Same goes for the pretzels.) You'll feel good about "being there" for your fellow traveler, they'll be saved some embarrassment, and it might even lead to a spirited conversation about the merits of honey- vs. dry-roasted.