This is particularly the case with respect to light aircraft and horizontally opposed piston powerplants.
I'm not sure I understand what it is you are trying to make clear here Guppy: Light aircraft - yes they usually have piston engines, but does it make any difference to the carb whether thay are of the hoizontally opposed variety? Suerly the carb doesn't know what piston line up the manifold leads to?
As an aside, many here will know there are some older variety of powerplants that have contiuous carb heat applied by design, and without any control linkage to the cockpit.