Indeed. That is true for people with or without kids. If you are consistently late, you are doing something wrong. Might be not enough time, could be an unrealistic start time, who knows. But if you are always late... as they say, brother that is on you.
It can act as a cure. I have some in-laws who are better than ever since they've been forced to adhere to some strict timings around school and childcare.
On the contrary, I found that the mornings I had a wide time margin, most things went smoothly and I could enjoy the time with my children. When I was nearly late from the start, things would go bad and soon even worse. I put it down to the difference in my patience and attitude in dealing with the inevitable little hiccups. In other words, I was to blame when we were late.
It's really disheartening to me to see that, immediately after you make a comment critical of rude behavior common to many parents, all the parents pile on and assume you just absolutely must be a non-parent.