For what it's worth, the slab in my shop is independent of the footers because it has radiant hydronic heating tubing installed in it. The slab is separated from the footers by rigid foam board insulation except for the top edge where the foam board tapers at 45 degress to the footer. The slab is on top of foam board, too. This method keeps it insulated from the outside. There is nothing next to the shop to which rebar could have been connected.
Control joints were cut in the 24' x 28' slab and slurried over for appearance. There are some ever so fine cracks along the control joints, visible through the epoxy coating on the floor. Lo these 7 years.
If it moves, it moves independently of the footers.
Chris