Because you’re asking the wrong questions.
Your team isn’t late because they all don’t use the same tools.
Your team is late because no one is helping coordinate the different tools.
The reason you missed that delivery deadline wasn’t because the bug count was too high.
It was because the feature load was preposterous and was never going to be met.
We shy from asking the wrong questions because the answers that come aren’t immediate and cannot be answered by one person.
You know if you’re getting the easy answer, you’ve been to the rodeo before, the next time you get the easy answer, don’t accept it, fight for the real answer.
It’s only then that you can start to see that you’ve been asking the wrong the questions all along.