I'd assume it's mostly down to men making more money and being less risk adverse than women. A fine means it's illegal for poor people, but the rich just pay the fine and do it again because they can afford to.
That article just isn't correct.
"Punishment" certainly has
some deterrence value. In other words, once you move away from the purely Kantian idea of moral desert to the utilitarian model, you find plenty of studies showing there is some value in deterrence.
The argument is over the signal- briefly ...
1. For deterrence to work, it has to be certain, and it has to be reasonably quick. In other words, the less likely you are to get caught, and the more attenuated the punishment from the act, the less effective the deterrence.
2. It has to be calibrated. For example, Finland is better at deterring speeding because they calculate speeding tickets based on income, and because they utilize more automated systems. America? Not so much.
3. People are not great at differentiating punishments- so there is various empirical studies showing that beyond a certain amount, additional "punishment" doesn't have much effect at deterrence. People might be rational, but the difference between a 15 year and a 35 year jail sentence (to use arbitrary examples) just doesn't register.
4. Finally, it has to be clear. If you don't have a reasonable knowledge of what the punishment is likely to be, then there is little deterrent effect.
All that said, no one can credibly argue that punishment doesn't have deterrent effect. If you don't believe the literature, just look at any society where the law has broken down.