IANAL, but AFAIK this sort of thing can take into account 'informal' experience as well as formal training/certification. I'm pretty sure attempting to game the system would be frowned upon.
Deliberately withholding training or certification in an attempt to reduce your own liability could possibly be considered negligent (because you're deliberately not conforming to accepted best practices, etc.)
That's a good point.
And I conceed certificate or the lack of probably doesn't chage the probability of getting sued. Once you wear that uniform or patch, you're fair game for the lawyers