Large contract manufacturers like Foxconn in China allow companies like Apple to pay only for labor to produce a specified inventory. Tasks are continually subdivided so they can be taught to a high turnover workforce quickly. And now with contract manufacturers able to effectively mobilize hundreds of thousands of workers on demand, companies no longer focus on whether or not it's feasible to recruit the requisite number of workers. The question is whether they can find the right thing to build.
Because the time from final design to production line is fast enough, companies have started to treat manufacturing as an on-demand service. Much like cloud computing, where additional servers are just a click away, it's now feasible for companies to purchase extra capacity to meet demand or scale down contracted production to limit inventory that will go stale.