There’s only one reason for being late to a meeting: poor planning. That’s why I see it as a sign of disrespect towards the person (or persons) I committed to meeting: they weren’t worth the effort to plan for carefully.
Simply put, I see being late as a deep personal failure in myself and deeply insulting to others, and one of my goals each year is to never miss a time I have committed to.
However, it’s important that I don’t hold others to this same standard. It’s one thing to hold oneself to a high standard, but another thing to hold others to that standard.
The former is a road to excellenc; the latter is the road to intolerance.