It's awful and rude isn't it?
I have a friend who does this a lot. The problem is, which she admits to, is that she doesn't think she will be late, until she IS late.
For example: Meet up at 10-30.
Most people will take into account the time it needs to get ready, the travel time and still have and extra 5 minutes for "just in case" in order to get the meeting point at that time.
Late people tend to think...Meet at 10-30, ah, that's loads of time. Get ready at 10 (10 minutes), get there (10 minutes) so I'll leave at 10-10 instead and be there on time.
It's annoying, rude, disrespectful and shows lack of organisation and time keeping skills. You can almost say that is can show contempt for the person waiting in really bad cases.
If meeting up with my friend I now make my own way to the meet up place and do my own thing first as I know she'll be late by at least 1/2 an hour. I never arrange to meet her at her house or my own because I can be sat there waiting for ages, even up to an hour in her own place as she gets distracted doing stuff that doesn't need doing.