AnFI
Helicopters fundamentally do not have to have 'FUEL SYSTEMS' with 5 fuel tanks with 6 fuel pumps 3 guages 4 non-return valves, 5 warning lights etc etc
Please stop refering to a helicopter as a complex machine and an aeroplane as simple.
'Simplicity' is all relative. The first aircraft I owned had the fuel tank in front of the cockpit and the gauge consisted of a cork on a welding rod poked through the filler cap. It never failed and there was no need to dip or sight-check the tank as you could feel the splash of the cork. The main fuel pump was an engine driven diaphragm with a car-type electric diaphragm as backup. The aircraft is still flying after nearly forty-five years service, with no reportable incidents, which makes it one of the most 'reliable' aircraft flying. Or does it?
As for fixed vs rotary wing, as a kid I used to make free-flight glow-plug model fixed wing planes (designed to be highly stable in all axes). They came down in a corkscrew after the engine stopped, of course, which puzzled me as a kiddie. I've never heard of a free-flight helicopter with no R/C or some kind of stabilising device (mechanical or electronic gyro,....). Even the simplest helicopter has far more moving engineered parts than a fixed-wing.