The operators that specialise in this type of work genarally pay their pilots an hourly rate for hours flown and often a "no crash bonus" at the end of the season of say an extra $10 per hour for every hour flown during the season providing the pilot doesn't roll one up. Wreck one and no bonus for you. That should give you some idea of how the aircraft are flown.
The company I worked for lost about one per year with the causes being, tail rotor strikes (quite common to flare to low and put the tail into the scrub), overpitching, water in fuel (drums)' mag failures low level. In my time there no accident was caused by mast bumping.