Historically Jet A-1/AVTUR has always been cheaper than AVGAS I would imagine that this is due to some agreement between Airlines and governments to keep Duty on Jet A-1 low for the good of the industry and economy

I shouldn’t think so; jet fuel is simply much cheaper to produce than AVGAS.

As an operator, the fuel price rise has an impact but it really is quite small in comparison to everything else

In New Zealand maybe, and also depending on the type of aircraft operated. AVGAS costs almost €2,50 per litre in Germany now!

I think the largest impact will be seen and felt among the light vintage aircraft, where fuel costs constitute a higher proportion of the operating costs. You should see the amount of SE aircraft currently for sale in Germany at the moment!