Not forgetting the other A109 that suffered an accident, flown by a PPLH holder in what could be described at best as very marginal VMC. The pilot probably attempted to fly an ILS, for which he was neither qualified or trained. Or another that quite a few of us in the industry know about - another A109S hit the ground and bounced, at night whilst trying to land in low cloud/fog in a remote area; thankfully not too hard a bounce such that the pilot got away with it, but the aircraft didn't fare too well.
People always make mistakes, be it whilst flying, driving, walking or whatever. Increased legislation won't prevent many of them. An AOC holder has a responsibility to monitor the safety of all involved, but that won't ever prevent professional pilots making errors of skill, or judgement of a situation once airborne.