It is cheaper to have a Bizjet sitting and or based offshore.
It is cheaper.
The point is CHEAPER.
Unless you are only doing Australian legs, then it may be a benefit to rego and have your jet onshore.
But in business often, a key factor is cost.
And offshore is a easy way to save many $1,000's in just on single ticket.
That has an effect on Bizjets and why folk don't "step in" to them, often in Australia the cost is high.