I think your 90% is wrong!
It would appear that Redrow do have a problem on several of their sites though, if this forum and my forum is anything to go by.
The NHBC inspectors should be checking this and not "finalling" any new homes with DPC less than 150mm above finished ground level.
I would agree that house builders, their site managers, the trades they employ and to an extent the NHBC site inspectors don't care.
wrong in what way, are you saying 99%