I am also perpetually late. I have ADHD, which sounds like such a cop-out I know, but I really do have poor organizational skills and time-management and I beat myself up every single time I'm late to something. I'm better at it than I used to be (yay behavioral modification!) But I've still occasionally shown up 15-30 minutes late having had to compose myself in the car from crying over being late YET AGAIN more times than I can count. It isn't because I'm trying to be disrespectful or that I don't value the other person's time. It really isn't. I don't mean to be rude! But I consistently underestimate the amount of time it will take me to be ready, or do something, or get out the door (if I even get out the door in one try.)
I've had many friends who just...tell me to be there earlier than I need to. Yes, I am an adult. I understand what this means.
So, many apologies on-time people! Some of us try, we really do!