Unfortunately this started back in the 80's but was no where near as bad then. I know a cattle station manager who did almost all his business in the Cairns area until fees started going up. He moved much of his extensive business requirements to Mareeba way back then.
There used to be several "pie vans" that were kept viable by the very active GA side of Cairns airport. Not to mention things like Snap On Tool businesses, kiosks etc before you even look at general business the airport attracts to Cairns from people on the Cape.
Well, there is a good regular bus service to Cairns from Mareeba that doesn't cost an arm and a leg. There are reasonably priced hire car businesses in Mareeba before you even look at the larger Australia wide hire car businesses which are in Mareeba as well. It is a pleasnant and not very long drive if you really do need to go to Cairns.
In general doing trade in Mareeba, from my personal experience, is lower cost than Cairns. My personal experience includes building my own houses a few years ago and obtaining all materials and required "Tradies" in Mareeba rather than Cairns for that reason. In fact other than to do a renewal that requires a 3D approach there is not much reason to go there these days.
I have no vested interest in Mareeba and in fact live in the Brisbane area for work at the moment and have for a while but I do know the area well over several decades. I figure "Cairns" in many way has very much shot itself in the foot.
The lovely tropical ambience, architecture, NQ people that was once the attraction that developers etc exploited for the dollar has largely been destroyed by that development often in a very exploitive manner. Not by all, but that original appeal is generally no longer there! Many of the laid back NQ characters moved to the"Tablelands" themselves for these same reasons.
Cairns Airport itself was a vibrant and socially active fun place to work. I hive of active businesses of many types not just direct Charter and aircraft.
Alas it is no longer, it has been very much throttled.