Very few people have a decent reason for being late for virtually every event.
As pp's have said, most mange perfectly well to be on time when it really matters (work/flights etc).
It's incredibly rude and what's worse is when they try and brush it off as some sort of cute quirk of character.
I had a friend like this and for a while simply dealt with it by giving her a time 15/20 mins earlier than the meeting time.
She'd still often be late.
I just got fed up with it and cooled the relationship. It's not fun to be the person waiting around for up to an hour because someone else cba to be organised.
Shitty excuses about waiting for the tumble dryer to finish (why not put in on earlier?) or waiting for a delivery (leave in a safe place or don't arrange to go out at a time when you need to receive goods?) Etc etc
It absolutely sends the message that their time is more important than yours and thus they are more important than you.
I don't buy for one minute people saying they can't help but be late all the bloody time.
You simply can't be fucked to get your arse in gear and be organised.
If you had to be at a certain place and time so someone could gift you £1m I'm damn sure you'd manage to be on time.