Developing software has all kinds of metrics that show the team if the progress is in the right direction, effective, and future proof.

How is it a program like DARE could have gone on for so long without peering into their own performance metrics to see if the program had any value?

It's a rhetorical question. It's obviously political. A group of powerful people banked their political cred on the concept and was unwilling to admit defeat. Just like the entire drug war.