In some cases it does. The good examples would be the white pelican and peregrine falcon. Peregrines I know well. I'm a bird guy. For 30 or 40 years we looked at the threats. We did captive breeding. We worked to protect critical nest sites, and we put captive-reared peregrines back in, a process called hacking. Eventually the endangered peregrine was bumped down to threatened. They're doing fine. They've responded. We had there an example of the main threat, which was toxic chemicals—the dirty dozen chemicals that caused their eggs to thin—being addressed through regulation and industrial practice, and because we sustained the full spectrum of efforts in the recovery strategy for 30 plus years, which is the ecological timeframe that counts for that particular species, and we succeeded.
Sure, it's costly, because when you let species slide down almost to the edge of the cliff, the longer you leave the preventative measures, the more costly—politically, economically, and ecologically—it is to actually bring them back up again.