Speeding isn’t an individual phenomenon, it’s a group phenomenon. Groups of drivers peer pressure each other into speeding. Choosing not to speed can result in aggressive drivers tailgating you and hurling obscenities at you.

Designing streets to be physically impossible to speed on (narrow, winding roads) is the ultimate deterrent for speeding. People respond better to feedback the more immediate it is and there’s nothing more immediate (for a driver) than physical obstacles that threaten to hit your car. Getting a speeding ticket in the mail a week after the incident is such a long feedback cycle that the driver is likely to blame the speed cameras, not their own driving.