Gaunty, I agree, the mining types do like jets. No doubt about it.
BUT, jets these days are being built for the European and US market, places with bigger runways and particular climates - not to mention demand. Places like Argyle, Karratha can handle jets... but even 146s struggle on hot and humid summer days. The ERJs for example just couldnt cope with the WA summer conditions.
Qanpulse hit the nail on the head in his comments.
The F50s are doing just fine for the types of routes they fly. Whats an extra 8-10 mins in time really worth when you are only flying into places like Leonora and Leinster.
My 2c