Mate, I truly dont know how they deal with it.
I guess its pretty obvious at a tech inspection if your car smells like deepheat or simple green lol . I'm not sure why it was banned in the 1st place.
Quite honestly I dont even know if the stuff is available over the counter here as I havent ever tried to buy it and have never felt the need to.
You just have to try to make the best of your setup.
I know at club level it isnt and in my experience hasnt ever been an issue.
Maybe some other kiwi driver would care to chip in here with an answer for you.
I can see why there would be resistance to banning it their cause its hard to take a step back when you are used to having/using the stuff.
I do believe though that changing the rules at roar (or whatever rules you run) level is the best way to deal with it.
The one thing you can guarantee is that the companies that make the stuff only care about your dollar not the long term effects on your health.
ps. wish you did live here mate, I need setup help lol, cant sem to get traction