Wire gives a concrete pad an amazing amount of strength when installed properly, unfortunately, it's rarely done properly. What happens is it's layed out on the ground or sub base just fine. Then the crew pulls it up when the concrete is being dumped. In theory, this should work, but in reality, the wire mesh never makes it to the middle of the concrete. In a few places, it might be near the top or even come out of the top, which is bad, but most of the time, it's in the bottom of the pad. It is VERY DIFICULT to get wire mesh in the center of the pad. Of course, you will have no way of knowing this until it's tore apart. If you have cracks, the contractor comes up with one of a dozen plausible excuses why it's not his fault. Only when you cut it up do you realize why it's really cracking. All cement cracks, but with rebar or wire properly installed, it doesn't lose it's strength when it cracks.
Eddie