I don’t think many people have a realisation of just how fantastically reliable people are in general. To get the humanoids to replace people will require mechanisms/wiring that approach these fantastic reliabilities.
For example, I think you could argue the automobile could have been dreamt up in concept many times; however, it took innovations such as SKF’s ‘frictionless’ wheel bearing; and the pressured ‘hydrostatic oil’ bearings of the pistons and crank to make cars a ubiquitous reality.