I think an important point here is that Frank did not design the R22 for mustering - he built it so every citizen could have his own personal helicopter. The reason it get used for mustering, flying training et al is because it's cheap - not because it's the best aircraft for the job.
You could buy a Skoda and try to run it for 200,000 miles without proper servicing in freezing conditions, always fully loaded and with a heavy right foot but you would not be surprised to see it break down - but it was much cheaper than the Volvo which would shrug off such treatment and just keep going.
Every time I've flown a robbie I have wondered how such pi**y, flimsy little blades kept it in the air just flying straight and level so I'm not entirely amazed that they suffer when they are constantly loaded in ops like mustering.
I bet those cattlemen don't buy cheap trucks - I bet they buy something that's built for hard work and abuse - the same shoud go for their helicopters.