I'll bet you it has something to do with the cord and plug type. Not sure, though. But , is that permanent? I know some still plugged in today that were wired in the 80's
It does have exceptions.
Cord and plug is in same section but different criteria, also not considered permanent. Permanent is what might commonly be referred to as hardwired.
Lemme look.
Okay, looked. My guess is because that's how cords are made, and they wanted to mimic that.
More likely is that it might somehow be a way to reduce accidental energization of the chassis.
Mobile homes have required non-bonding and 4-wire major-appliance circuits for almost forever.
Item 1, could be, but find it hardly a reason to make it a rule.
Item 2, not sure as the chassis has to be bonded to the grounding bus and conductor as listed in another section. And not sure how having a insulated ground would help this.
Item 3, that's true, no neutral/ground bonding.
Trying to discover the underlying reason for this installation to be different than a similar installation in a non mobile home. Can see needing to justify it to a GC sometime.