What causes accidents are not the cars and conditions you see, but the ones you don't.
Humans aren't machines, they make mistakes. And cars have a lot more blind spots than we realize.
That's why we have rules. If we are predictable and follow the rules, even when we don't see anything that could stop us from taking a shortcut, then we're being considerably safer.
Keep in mind that, on the road, it's not just your own safety you need to ensure. An accident can also harm other people, so the more reason to prevent them.