A basic plane will fly without any SAS and also without a pilot, because it is dynamically stable in all axes.
A helicopter will NOT fly without a pilot because it is dynamically unstable in pitch and roll. The pilot has to fly it all the time, so if any SAS is fitted it would be working like a cut snake all the time. And for a chopper, they are expensive, which means you usually won't see one in anything that isn't IFR or the size of an AW109 or better.
"An airplane will fly, but a helicopter must be flown."