If you could make them think about and want to work in your factory the way they think about and want sex, you'd have a full roster every shift and would be turning people away. Such an oversupply would naturally see the value of that labor drop to near nothing.
If this were true, prostitution wouldn't exist because no one would be willing to pay for sex.
Prostitution exists because of the things I've described, not in spite of it. Yes if sex were truly free and easily available then sex work wouldn't be as lucrative as it is today. And, as you say, there'd be no need for it because everyone's already getting their rocks off.
One can dream...
Everyone is equipped with the necessary hardware to work in my factory. Barring health issues it costs nothing. Why does your labor need to have "value"?