Childhood – curiosity

Doctors if there are. Tell me, why is there such a phenomenon as a prothesis of the hand? Especially with motorcycles. Is the brush a purely mechanical system, or do I know something? All her muscles are found around the radial bone, below the wrist only a willless puppet, for which the tendons are pulled.
Why do wildly expensive systems, when endoprostheses already exist even in series, and from soft tissues you can form at least a sickle, at least a sickle? What prevents titanium endoprostheses and a piece of skin with fatty fiber from making a new brush and sewing tendons to it?
Okay, it is easier. What prevents the tendons in general from sewing to some skin-throughing stitches or piercings that can move a purely mechanical prothesis gloves? Yes, at the point of contact, the mole will be filled, but it is better to use your hand sometimes than to sit without a clove at all and wait for the sea weather and all kinds of wonders with bio-flow control.
Tell me, I know for sure, there is at least one here who tells a story that is very obscene, humorous and with a fire. Enlighten the dark and distant man.