The tricks up my sleeve... Methods I may implement for better FE.

[Snax]

landspeed has it correct. It's about safety margins. While a higher compression motor can afford the random detonation here and there, a turbocharged motor is far less tolerant to it as cylinder pressure is increased. One good detonation event can literally blast the piston ring lands apart or worse. That simply doesn't happen with your average NA motor. So in the case of the turbo, they map extra fuel in to mitigate that possibility as well as reduce timing advance.