Humanoid forms are less efficient than specialist ones. It is a nonsequitor that chasis shape will somehow make a slave economy. But even if improbably sapient

Humanoid forms are less efficient than specialist ones. It is a nonsequitor that chasis shape will somehow make a slave economy. But even if improbably sapient robot slaves were a thing part of what made slave economies stink was not upgrading their tools and efficiency. When the tools are designed by a highly educated workforce that pitfall wouldn't apply.