It drives their behavior because it is directly linked to their survival.
We might think our dog’s fear behavior may be irrational. But we as humans have irrational behaviors as well and respond in many different ways.
It is vital that for dog’s and human’s we help them overcome fear through desensitization, counter-conditioning and thresholds and not just expose them to things and places that frighten them and expect them to cope and learn to overcome their fears.