My father was pretty even-tempered, and didn't often get angry. But his sister was always, always late for family gatherings, and that could really set him off. (Still does it, she was late to the last funeral we were at, as well.)
As a result, I am nearly always on time for everything, and I also get annoyed with people who don't manage it, and have been known to demand apologies at work. If you've got a 10am meeting, why would you wait till 1 minute before to fit in everything from popping to the loo and making a cup of coffee before sauntering along to the meeting room? I find it so rude that people can be so inconsiderate of other people's time like that. I know some things will always get in the way - really bad traffic problems, or major customer-facing problems at work or so on, but it's not usually things like that, it's just they can't be bothered to make a bit more effort.
The one which really, really annoys me is a manager who cancels meetings last minute, or starts them up to 20 minutes late and so on. And yet, when it was a meeting including his manager as well, he was absolutely on time. It just proves he can do it, and the rest of the time is just bullying and manipulative, because they're people who aren't worthy of him (in his view. Most people on this planet are worth more than him.)