The Universe is Indifferent

I think the "etiquette" part you're referring to is what's known as "being fashionably late". It's not really "etiquette", per se, but I see where you're coming from.

I do agree that sometimes things just work against you. You could leave ten minutes early, or a half-hour early, and still be five minutes late depending on traffic. Sometimes it's hard to predict, especially in inclement weather.