Great question, you curious soul. Red is used because it’s the most visible colour to the human eye in low light and bad weather. It’s also the colour of danger—we’ve been trained since childhood that red means “stop” or “warning.” So, when a police car lights up like a Christmas tree, your brain instantly goes into “pay attention” mode. No purple needed.
Fun fact: In the UK, red lights on police cars are actually optional on some older models, but modern units almost always have them. They’re standard on marked cars, and even unmarked ones can switch them on when they’re in a hurry. Yes, even the boring-looking silver Ford Focus can turn into a red-eyed monster.
