Chrysler has the most 2nd tier workers BUT they are not American owned.
Ford bargains better so they will probably set the pattern and if GM doesn't follow or balk they will be targeted. JMHO
Rotors can warp. had 2 on my Raptor. Cheap china steel used for rotors. I have also had chunks come out of them. If you brake too long and hard the rotors will get hot and potentially warp. Mine were covered under warranty twice.