Chronically late people irritate me almost beyond description. And the reason is that the person (and their defenders) don't give one tiny darn about anyone else. They don't care that you are inconvenienced. They don't respect anyone (you) or anything (a concert's starting time). They see themselves as important and everyone and everything else as subject to them. They believe that their lateness should be honored because they want it. In short, they are IT, and the rest of the world can kiss their ...watches. 
Edited to add ".....can kiss their ...*broken* watches".
The ONLY times that I remember being THAT late were when there was an accident involving three semi-trucks blocking three lanes north and three lanes south on an interstate highway (and a Life Flight helicopter - I phoned in to let my supervisor know that I was stuck in traffic....for over two hours); when a car broke down as we were making a 90 minute trip from our house to Galveston (Lil Sis left her house to meet us - we had a cell phone, she didn't, and we ended up getting a taxi, a rental car, and a tow truck that day to get to Galveston, then get the broken down car home to a repair shop - radiator trouble).
VorGuy has a habit of thinking that we can make a trip in the same time or less as the "average trip time" on the driving directions sites. I always pad a bit because of the need to stop for a bathroom break (menopausal me); possible need to fuel up if it's a spontaneous trip; or just because nobody is ever ready to leave early.....if I am, someone else won't be. Or they'll have forgotten something and we have to make a stop to shop for a replacement if we are too far from home to turn around and get it...
If it's sunglasses, we stop & shop - wallets we go back for......