I'm never late for work because my work comes to me! I'm a nanny for a 5 month old baby, and she comes to my house each day at 8:00 am. Her parents are good friends of mine, and they have a key to our house so even if I were to oversleep some morning they would come right in, wake me up, and drop off the baby. (edited to add: not that this has ever happened!)

I love my job!
The parents are very prompt people, too, and they respect my time. Mom drops off the baby in the morning, and dad picks up in the evening, but if for some reason the dad gets stuck in a meeting, he calls the mom to let her know and she'll leave work to pick up the baby. His job sometimes schedules meetings on him like that, but hers is more flexible with hours.
In general, though, I'm a "get there early" person. I've had my share of late times, but for the most part I prefer to arrive 5-15 minutes early depending on the situation/event. I've done retail, temp work, office/clerical, day care, children's ministry, college student ministry, taught voice lessons and taught preschool. I rarely was late for any of my jobs, and I didn't call in sick unless I was too sick to come or if my illness would be a risk to the babies I took care of in the day care.
I can totally understand why that sales clerk was written up - if I were her supervisor it would have happened earlier!