Boutique motor manufacturers put that much thought into their motor design (skewed winding slots, optimized winding patterns, skewed magnetization of the rotors, tuned air gaps, etc.), but the big brands don't. That level of optimization is not cost-effective. Unlike commodity products like washing machines or water pumps or HVAC blowers, which are manufactured by the tens of thousands and all held to the same specifications, RC cars are made in small numbers and every owner wants slightly different performance.

The big RC brands just buy motors in bulk from the same factories that make motors for all other types of small devices, with generic "good enough" specifications. Energy-efficiency is not a primary concern in RC, except in some especially-competitive racing niches. Most people just deal with laggy motors by using higher-voltage batteries to shove more amps through their motors. Even people who pay attention to torque curves and throttle response just tweak the settings in the ESC to get the motor to run the way they want, rather than hunting around for a motor perfectly-optimized for their needs. It's simply easier to deal with the concerns you're mentioning by adjusting software settings rather than replacing hardware, even though it's less energy-efficient.