You go to the mechanic and tell them your car won't start - nothing happens when you turn the key. You ask them how long it's going to take to fix and how much it will cost.

They don't assume it's the starter and tell you it will be $400 for parts and labor. They tell you it will be $150 diagnostic fee and the diagnostic will take two hours. Then they call you and tell you the cost to fix and time it will take.

For whatever reason, software engineers don't have the luxury of doing a diagnostic. We are made to guess up front and assume it's the starter, when we really have no idea what rat's nest is under the hood until we look.