Many a local government is known to trap people with no good reason. Place a speed limit sign somewhere it's hard to spot from the road and the road does not in

Many a local government is known to trap people with no good reason. Place a speed limit sign somewhere it's hard to spot from the road and the road does not indicate a speed limit by e.g. reducing lanes, place a few strategic cops and loot everyone who doesn't have a navigation system with speed hints. Bonus, use the opportunity for some nice civil forfeiture scams.