If 'hubby' has a 3mm HSS drill in drill set on "ramming speed", and
just presses a bit, it'll go through most stuff easily.

Possibly, but you're not expected to use a 3mm HSS in a wall. A masonry bit
might be a more reasonable choice and these are as useful as a piece of
celery for drilling into thick walled metal conduit. The rules are to give
reasonable protection against foreseeable actions, not to save people
specifically intent on commiting suicide.

Besides, have you ever tried drilling metal? Even a quality bit won't go
through like cheese through a thick walled pipe. The difference in
resistance will be collosal compared to the substrate material
(plaster/brick) and be very obvious to the perpetrator.

Christian.