Mazda uses a four sensor, four channel controller to control each wheel individually. Early ABS systems often combined both back wheels on the same channel. And Mazda's system is integrated into their dynamic stability system (as is any car with ABS and dynamic stability). It's also integrated into their Electronic Brake Force Distribution system which measures the load on each wheel and distributes braking force to suit. This dramatically reduces the situations in which the ABS needs to take over in the first place.
But what I was really referring to was the valving (and software implementation) of Mazda's ABS is more refined compared to many earlier cars I've driven. It is less obtrusive, it is harder to get to the point where it is necessary for it to kick in and, when it does, it does it in a more refined manner. I believe it simply reacts faster and less abruptly. Also, depending upon the design of the hydraulic valves, pumps and lines (and also the specific algorithms used in the brake controller's computer), the brake pedal will have different feedback upon activation of ABS. Earlier systems were very crude in this regard.