I wanted to let this one go and I nearly did but.......
In my experience it boils down to maintenance/repairs vs performance. For maintenance/repairs I am happy to let the shop do what they have to do, and there are a number of shops who do this and do it well and to be fair dont need to look at performance work because they are very busy fixing Euro cars that have proven to be somewhat less reliable than their Japanese counterparts. A great business model really.
For performance, parts are often the hurdle; they are just not available here and workshops as noted above are focussed on repairs maintenance. Workshops often default to parts available in NZ which may or may not be the best solution for a performance upgrade and with DIY tuning options like COBB, MHD etc it is fitting and final troubleshooting/tuning that is wanted. (This of course may lead to maintenance/repair work as components fail when under stress)
The problem with performance upgrades is that it is often the domain of the Flat Peak crowd with a clapped out Japanese sh*t box, no money and big dreams. But in the HSV FPV world a lot of tuners emerged who could meet the demand of the cashed up bogans and that segment were quite willing to pay, as a result that segment went upmarket and got away from its bogan/hoon roots and became professional.
What we have in NZ is a lack of Euro tuning shops. Audi, VW, BMW and to a lesser extent MB now all have forced induction engines and chassis that respond well to basic upgrades. Forced induction is the cornerstone of the tuning world. We need a few shops who understand that mindset and can provide solutions. Fair to say we dont have that at the moment.