Not sure about this study, by my good friend John Nye. Summary from WSJ:
George Mason University economists Garett Jones and J.V.C. Nye set out to solve a riddle: What makes someone likely to obey the law in situations where there’s no chance for punishment? Before 2003, diplomats enjoyed just this type of impunity when parking on city streets. Hundreds of United Nations representatives and foreign consulate officials in New York were free to ignore parking tickets issued by police without fear that their vehicles would be impounded.
A federal law took effect in 2003 giving local authorities the power to pull diplomatic plates from cars with too many unpaid tickets, introducing the first real consequence. Unpaid tickets plummeted as a result. But even in the freewheeling era of diplomatic immunity, not every nation’s diplomats ignored parking tickets just because they could. As the economists note:
Delegations differed widely in their scofflaw tendencies: The median diplomat averaged 8 unpaid tickets per year, the standard deviation was 33 tickets per year, and the maximum was 250 per year (from the Kuwaiti delegation).
The study itself...
Would have thought that "IQ" would be standing in for a national culture of rule of law, and voluntary cooperation. In other words, market systems.
So my hypothesis is that countries with highly developed market systems would be those that have fewer parking tickets. The "IQ" correlation is spurious.