CANTER does so much good - and so do other reputable organizations just like them. CANTER isn't being "used that way" -- it's really about match-making (listing available OTTBs needing new careers/homes):
CANTER enables thousands of OTTBs and thousands of loving horse owners to find each other. Many matches are made in heaven, many love stories are written and many, many happy "ever afters". Of course, not all matches are made in heaven. Apologies for the match-making metaphors - used only to underscore that CANTER is a good thing.
CANTER is merely a volunteer group that advertises racehorses that are retiring from the track so they could potentially get a second career. CANTER is not a "rescue" organization per say; although they do take on some of their own rescues (which are a different entity from the trainer's listings).