There are multiple reasons why an insurance company might deny your claim. To be more specific, the at-fault driver’s insurance company might choose to deny your claim. The most common reason is word versus word.
Consider a scenario where you and the at-fault driver both approached the same intersection. You had a green light. They had a red light. They ran the red light. They hit you in the middle of the intersection, but they told their insurance company that they were adamant that they had the green light, not you.
The insurance company is going to do what they have to do protect their insured, and they are going to believe them. Also, they are looking to act in their own best interest, so if they have a reason to deny a claim, of course, they are going to deny it.
One of the big reasons why they are going to do it is if the stories are contradicting each other, and they do not have a reason or witness to say otherwise. If they are unable to tell just by looking at it, they are going to deny the claim.