Edge, this is not unusual. There is no metal in the wiring method, box or even the plumbing. I am not sure where the path would be to trip the O/C device until the dryer does get hooked up.
These houses are built on a slab with an isolation membrane under the steel framing. The panel will be on a block wall in the garage. Everything is in Romex with plastic boxes. If they don't get caught with a luminaire having to go directly over a stud, requiring a pancake box I am not sure there is any way the steel gets bonded.
In commercial with EMT and steel boxes this is not a problem. It gets bonded all over the place.
I bet we start seeing metal framing coming under 250.104(C)
The contractors probably could have made this issue go away if they just used steel boxes for the dryer and the range. That would give them some fat EGCs bonded to the steel with a few pennies added to their cost. If we get required bonding under 250.104(C) they will be stringing #4 or larger all over.
