On today's city roads it is just not safe to ride day or night without active and passive lighting. Meaning reflectors and lights front and rear. There are more ways for drivers to get distracted today than there were even just 10 years ago. No, reflectors and lights are not a silver bullet but they do increase your odds of being seen. That just may save your life some day.
Your best defense is still your brain with the aid of a rear view mirror on your riding glasses. Your brain should be telling you reflectors and lights......