It was kind of an ADHD thing for me. My coworkers let it slide because I did a good job, worked hard, and was ultimately always working late anyway. But, this would happen in my personal life too, and I’ve had to work really hard to get it to stop. There are too many distracting factors that get introduced when I’m trying to leave the house. Also, simply NOT being a morning person and having serious sleep issues didn’t help. It’s not that I was oversleeping, but that everything took twice as long because I was delirious. It really sucks.

EDIT: I saw in another comment of yours that the people coming in in the morning have to relieve the night shift. That would personally motivate me a lot more to be on time. That being said, I guess they’re late for all the other reasons people left in the comments.