Not just error-prone ... these things are seriously dangerous: one mistaken move and they can take someone's head or limb off! Any American roboticist will tell you that humanoids are a decade (or more) away from being practically and safely used alongside humans.
China seems to be falling for the classic trap of socialism: the government has been able to manage the economy successfully (just as the Russians did ... for awhile), so they think they can continue to do so when technology (or anything else) changes.
But humans make mistakes when they try to predict the future (markets do too of course, but they make a lot less mistakes). The Chinese leaders think they can make humanoids happen the same way they took over the electric vehicle market (through heavy government support/spending), but government support can only influence the pace of technology; it can't fundamentally change it.