So. My usual mechanic says that the anti-lock braking circuit is draining the battery. Pulling the fuse for that circuit stops the problem, but disables ABS.
According to the service manager at my garage, ABS is not all that important anyway: it rarely even gets used, and when it does get used, it can often increase your stopping distance. He dislikes ABS, and says that if I have to pay more than $200-300 to get it fixed, he’d suggest not getting it fixed at all — if nothing else relies on the ABS fuse. If Mazda says that the ABS system can be disabled without causing additional problems, and it’s expensive to fix, then the mechanic I trust says “leave the damn thing broken”.
The jury is still out. Jodi and I can’t make that decision until we have information from the dealership. Speaking in generalities, I’m inclined to take my mechanic at his word. I learned to drive on a car without ABS, and the braking system felt firm and powerful when I tested it on the way to the dealership.