Maybe on the Mustang, I was just basing it off my Mom's Edge.
There was one of the Mustangs a year or two (or three?) ago that had a "track key" or some such thing that you paid extra for to turn "on" certain features.. (or, perhaps turn them "off" as the case may be for traction control, etc.)
I figured that was how the "My Key" thing worked. The "regular" key had all the nannies turned on by default and the "My Key" would let you turn those things off.
I'm not in the market for a Mustang. So, I haven't kept up with all that stuff very much.