That is true. However, I don't think one needs to be "reckless," a rather strong word, to be "not sufficiently concerned with the harm I might do."
Driving is a matter of habits, and if people develop the habit of exceeding the speed limit, passing unsafely, or failing to stop at stop signs, they are a threat to others.
It comes down to whether a person chooses to think of herself first, or to consider others first, even at a cost to self. Driving the speed limit, as a rule, does no harm to the self, and it decreases the risk of harm to others.
All that is true, but “sin” still doesn’t come into it. Moderation in all things, right?
I can drink a beer or two without being a drunkard, and I can go 10-20mph over the limit at 3am in the New Mexico desert without being a hazard, and I can drive through a red light that refuses to change at midnight at a completely empty intersection (that one has happened to me on several occasions).
It’s all about applying some common sense and judging the individual situation.