Money. No one is betting on other equine sporting events besides Thoroughbred, Quarter horse or harness racing. It's the states that won't cede to other entities the ability to regulate (or to not regulate in this case) an activity that brings in to the state coffers a tremendous amount of money. It's always about the money.
That makes sense - shows you how much I actually know about the racing industry. The sad thing is that I think more people would be willing to adopt and re-train off the track horses if it wasn’t so expensive to do it, unless you have your own facility. A friend and I found this out the hard way...people were giving away Thoroughbreds, but when you count the board, extra feed, vet care, farrier, etc., even if you were able to resell the horse for $5000-$10,000, you would still be lucky to break even after all was said and done.