Extra fuel is insurance against unforeseen circumstances. Nobody likes to pay for it, but you have to have it. It’s the cost of doing business and a hedge against a potentially MUCH larger expense. A return to gate, a divert or something potentially disastrous. We hope to never use our insurance. Should we be penalized for not filing a claim every time we fly as well?

There are far too many moving pieces to plan and control everything. All it takes is several minutes of “turn left 60 degrees for spacing” to burn through any cushion of fuel.