So if you recognize that they all have issues but that some are just better at hiding them, then what is the difference you're referring to? The appearance of being buttoned-up, or the silent claim that some make as to being normal? Is it the worship of normalcy itself that's bothersome? I think that would be understandable, because it's a false ideal that by its very nature sets people up to fail.
I've never encountered a person whom I witnessed to be discernably "normal", whatever that can even be said to be. I certainly have friends whose lives appear somewhat without fault to the naked eye, but in my mind one need only get to know someone a little bit to notice they have issues. Closest I think there is to normalcy is people who are actively dealing with their stuff -- but they still have stuff, and I think we're all just sort of hanging on somehow. Those that make the biggest show of having all their ducks in a row are often the most distraught among them, in my opinion.
Maybe it's a bit like the Easter Bunny though. I don't believe in normalcy, and don't specifically see it in people, and as a result I get no basket of pastel-colored treats one Sunday each Spring. Iffen you get my drift.