Some people don't think they need to take care of a cracked windscreen. They claim they can drive just fine, as long as they avoid the police and are more careful. The cost of windscreen replacement, they say is too high.
Sadly, while the cost of windscreen replacement can be a bit expensive, it is only a small pittance. By comparison, there are many risks to driving with cracked glass right in front of you.
Cracked glass can seriously hinder your visibility. The damage impairs your ability to see your surroundings. Such a situation can create a blind spot as you drive, or make it difficult to identify what's on the road.
You may not necessarily intend to, but the fractured visibility means you are a moving road hazard to everyone else.
Data suggests that fractured glass is also related to delayed reactions. People spend fractions of seconds more on identifying what's on the road or their proximity to the vehicle. It messes with a driver's instincts, and the delay can cause accidents.
Modern windscreens are attached by adhesive bonds to the body of the car, making it tied to overall integrity. Damage to the glass can result in higher risk of a collapsing roof in most modern vehicles.
A windscreen is also designed to provide a small measure of protection in the event of an accident.
Of course, if you drive around with a crack in it, that means the whole thing is compromised. While modern front windscreen glass won't shatter into thousands of tiny pieces, there is still a very real risk. The glass can absorb at least some of the impact, reducing the damage done to those inside the car.
A cracked window doesn't do as good a job. At the same time, studies show cracked windows make airbags, and other safety features less effective.